Methods for monitoring the formation and transport of an acidizing fluid using opticoanalytical devices

ABSTRACT

In or near real-time monitoring of fluids can take place using an opticoanalytical device that is configured for monitoring the fluid. Fluids can be monitored prior to or during their introduction into a subterranean formation using the opticoanalytical devices. Produced fluids from a subterranean formation can be monitored in a like manner. The methods can comprise providing at least one acid; combining the at least one acid with a base fluid to form an acidizing fluid; and monitoring a characteristic of the acidizing fluid using a first opticoanalytical device that is in optical communication with a flow pathway for transporting the acidizing fluid.

BACKGROUND

The present invention generally relates to methods for the monitoring offluids in or near real-time, and, more specifically, to methods formonitoring fluids prior to, during or after their introduction into asubterranean formation and/or to methods for monitoring produced fluidsfrom a subterranean formation.

When conducting operations within a subterranean formation, it can beimportant to precisely know the characteristics of a fluid or othercomponent present in or being introduced into the formation. Typically,the analysis of fluids and other components being introduced into asubterranean formation has been conducted off-line using laboratoryanalyses (e.g., spectroscopic and/or wet chemical methods). Theseanalyses can be conducted on fluid samples being introduced into thesubterranean formation or on flow back fluid samples being produced fromthe subterranean formation after a treatment operation has occurred.Depending on the analysis needed, such an approach can take hours todays to complete, and even in the best case scenario, a job can often becompleted prior to the analysis being obtained. Furthermore, off-linelaboratory analyses can sometimes be difficult to perform, requireextensive sample preparation and present hazards to personnel performingthe analyses. Bacterial analyses can particularly take a long time tocomplete, since culturing of a bacterial sample is usually needed toobtain satisfactory results.

Although off-line, retrospective analyses can be satisfactory in certaincases, they do not generally allow real-time or near real-time,proactive control of a subterranean operation to take place. That is,off-line, retrospective analyses do not allow active control of asubterranean operation to take place, at least without significantprocess disruption occurring white awaiting the results of an analysis.In many subterranean operations, the lack of real-time or nearreal-time, proactive control can be exceedingly detrimental to theintended outcome of the subterranean operation. For example, if anincorrect treatment fluid is introduced into a subterranean formation,or if a correct treatment fluid having a desired composition but atleast one undesired characteristic (e.g., the wrong concentration of adesired component, the wrong viscosity, the wrong pH, an interferingimpurity, a wrong sag potential, the wrong kind or concentration ofproppant particulates, bacterial contamination and/or the like) isintroduced into a subterranean formation, the subterranean operation canproduce an ineffective outcome or a less effective outcome than desired.Worse yet, if an incorrect treatment fluid or a treatment fluid havingan undesired characteristic is introduced into the subterraneanformation, damage to the formation can occur in some cases. Such damagecan sometimes result in the abandonment of a wellbore penetrating thesubterranean formation, or a remediation operation can sometimes beneeded to at least partially repair the damage. In either case, theconsequences of introducing the wrong treatment fluid into asubterranean formation can have serious financial implications andresult in considerable production delays.

Off-line, retrospective analyses can also be unsatisfactory fordetermining the true suitability of a treatment fluid for performing atreatment operation or for evaluating the true effectiveness of atreatment operation. Specifically, once removed from their subterraneanenvironment and transported to a laboratory, the characteristics of atreatment fluid sample can change, thereby making the properties of thesample non-indicative of the true effect produced by the treatment fluidin the subterranean formation. Similar issues also can be encountered inthe analysis of treatment fluids before they are introduced into asubterranean formation. That is, the properties of the treatment fluidcan change during the lag time between collection and analysis. In suchcases, a treatment fluid that appears unsuitable for subterranean usebased upon its laboratory analysis could have been suitable ifintroduced into the subterranean formation at an earlier time. Theconverse can also be true. Factors that can alter the characteristics ofa treatment fluid during the tag time between collection and analysiscan include, for example, scaling, reaction of various components in thefluid with one another, reaction of various components in the fluid withcomponents of the surrounding environment, simple chemical degradation,and bacterial growth.

In addition, the monitoring of source materials that are being used inthe formation of a treatment fluid can also be of interest. For example,if an incorrect source material or the wrong quality and/or quantity ofa source material is used to form a treatment fluid, it is highly likelythat the treatment fluid will have an undesired characteristic. In thisregard, monitoring of a source material can also be an important qualitycontrol feature in the formation of a treatment fluid.

In addition to monitoring the characteristics of treatment fluids thatare being introduced into a subterranean formation, the monitoring offluids produced from a subterranean formation can also be ofconsiderable interest. Produced fluids of interest can include bothnative formation fluids and flow back fluids produced after thecompletion of a treatment operation. As noted previously, thecharacteristics of a flow back fluid can provide an indication of theeffectiveness of treatment operation, if analyzed properly. In spite ofthe wealth of chemical information that can be present in these fluids,it has sometimes been conventional in the art to simply dispose ofproduced formation water or flow back fluids resulting from a treatmentoperation. As an added concern, the significant volumes of fluidsproduced from a subterranean formation can present enormous wastedisposal issues, particularly in view of increasingly strictenvironmental regulations regarding the disposal of produced water andother types of waste water. The inability to rapidly analyze producedfluids can make the recycling or disposal of these fluids exceedinglyproblematic, since they must be stored until analyses can be completed.As previously indicated, even when an analysis has been completed, thereis no guarantee that the sample will remain indicative of the producedbulk fluid.

More generally, the monitoring of fluids in or near real-time can be ofconsiderable interest in order to monitor how the fluids are changingwith time, thereby serving as a quality control measure for processes inwhich fluids are used. Specifically, issues such as, for example,scaling, impurity buildup, bacterial growth and the like can impedeprocesses in which fluids are used, and even damage process equipment incertain cases. For example, water streams used in cooling towers andlike processes can become highly corrosive over time and becomesusceptible to scale formation and bacterial growth. Corrosion and scaleformation can damage pipelines through which the water is flowing andpotentially lead to system breakdowns. Similar issues can be encounteredfor fluids subjected to other types of environments.

Spectroscopic techniques for measuring various characteristics ofmaterials are well known and are routinely used under laboratoryconditions. In some cases, these spectroscopic techniques can be carriedout without using an involved sample preparation. It is more common,however, to carry out various sample preparation steps before conductingthe analysis. Reasons for conducting sample preparation steps caninclude, for example, removing interfering background materials from theanalyte of interest, converting the analyte of interest into a chemicalform that can be better detected by the chosen spectroscopic technique,and adding standards to improve the accuracy of quantitativemeasurements. Thus, there can be a delay in obtaining an analysis due tosample preparation time, even discounting the transit time of the sampleto a laboratory. Although spectroscopic techniques can, at least inprinciple, be conducted at a job site or in a process, the foregoingconcerns regarding sample preparation times can still apply.Furthermore, the transitioning of spectroscopic instruments from alaboratory into a field or process environment can be expensive andcomplex. Reasons for these issues can include, for example, the need toovercome inconsistent temperature, humidity and vibration encounteredduring field or process use. Furthermore, sample preparation, whenrequired, can be difficult under field analysis conditions. Thedifficulty of performing sample preparation in the field can beespecially problematic in the presence of interfering materials, whichcan further complicate conventional spectroscopic analyses. Quantitativespectroscopic measurements can be particularly challenging in both fieldand laboratory settings due to the need for precision and accuracy insample preparation and spectral interpretation.

SUMMARY OF THE INVENTION

The present invention generally relates to methods for the monitoring offluids in or near real-time, and, more specifically, to methods formonitoring fluids prior to, during or after their introduction into asubterranean formation and/or to methods for monitoring produced fluidsfrom a subterranean formation.

In one embodiment, the present invention provides a method comprising:providing at least one source material; combining the at least onesource material with a base fluid to form a treatment fluid; andmonitoring a characteristic of the treatment fluid using a firstopticoanalytical device that is in optical communication with a flowpathway for transporting the treatment fluid.

In one embodiment, the present invention provides a method comprising:preparing a treatment fluid; transporting the treatment fluid to a jobsite; introducing the treatment fluid into a subterranean formation atthe job site; monitoring a characteristic of the treatment fluid at thejob site using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the treatment fluid;determining if the characteristic of the treatment fluid being monitoredusing the first opticoanalytical device makes the treatment fluidsuitable for being introduced into the subterranean formation; andoptionally, adjusting the characteristic of the treatment fluid.

In one embodiment, the present invention provides a method comprising:forming a treatment fluid on-the-fly by adding at least one component toa base fluid stream; introducing the treatment fluid into a subterraneanformation; and monitoring a characteristic of the treatment fluid usingan opticoanalytical device while the treatment fluid is being introducedinto the subterranean formation.

In one embodiment, the present invention provides a method comprising:providing at least one acid; combining the at least one acid with a basefluid to form an acidizing fluid; and monitoring a characteristic of theacidizing fluid using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the acidizing fluid.

In one embodiment, the present invention provides a method comprising:providing an acidizing fluid comprising at least one acid; introducingthe acidizing fluid into a subterranean formation; and monitoring acharacteristic of the acidizing fluid using a first opticoanalyticaldevice that is in optical communication with a flow pathway fortransporting the acidizing fluid.

In one embodiment, the present invention provides a method comprising:forming an acidizing fluid on-the-fly by adding at least one acid to abase fluid stream; introducing the acidizing fluid into a subterraneanformation; and monitoring a characteristic of the acidizing fluid usingan opticoanalytical device while the acidizing fluid is being introducedinto the subterranean formation.

In one embodiment, the present invention provides a method comprising:providing at least one fracturing fluid component; combining the atleast one fracturing fluid component with a base fluid to form afracturing fluid; and monitoring a characteristic of the fracturingfluid using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the fracturing fluid.

In one embodiment, the present invention provides a method comprising:providing a fracturing fluid comprising at least one fracturing fluidcomponent; introducing the fracturing fluid into a subterraneanformation at a pressure sufficient to create or enhance at least onefracture therein; and monitoring a characteristic of the fracturingfluid using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the fracturing fluid.

In one embodiment, the present invention provides a method comprising:forming a fracturing fluid on-the-fly by adding at least one fracturingfluid component to a base fluid stream; introducing the fracturing fluidinto a subterranean formation at a pressure sufficient to create orenhance at least one fracture therein; and monitoring a characteristicof the fracturing fluid using an opticoanalytical device while thefracturing fluid is being introduced into the subterranean formation.

In one embodiment, the present invention provides a method comprising:providing a treatment fluid comprising a base fluid and at least oneadditional component; introducing the treatment fluid into asubterranean formation; allowing the treatment fluid to perform atreatment operation in the subterranean formation; and monitoring acharacteristic of the treatment fluid or a formation fluid using atleast a first opticoanalytical device within the subterranean formation,during a flow back of the treatment fluid produced from the subterraneanformation, or both.

In one embodiment, the present invention provides a method comprising:providing a treatment fluid comprising a base fluid and at least oneadditional component; introducing the treatment fluid into asubterranean formation; and monitoring a characteristic of the treatmentfluid using at least a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the treatment fluidbefore the treatment fluid is introduced into the subterraneanformation.

In one embodiment, the present invention provides a method comprising:providing an acidizing fluid comprising a base fluid and at least oneacid; introducing the acidizing fluid into a subterranean formation;allowing the acidizing fluid to perform au acidizing operation in thesubterranean formation; and monitoring a characteristic of the acidizingfluid or a formation fluid using at least a first opticoanalyticaldevice within the subterranean formation, during a flow back of theacidizing fluid produced from the subterranean formation, or both.

In one embodiment, the present invention provides a method comprising:providing an acidizing fluid comprising a base fluid and at least oneacid; introducing the acidizing fluid into a subterranean formation; andmonitoring a characteristic of the acidizing fluid using at least afirst opticoanalytical device that is in optical communication with aflow pathway for transporting the acidizing fluid before the acidizingfluid is introduced into the subterranean formation.

In one embodiment, the present invention provides a method comprising:providing a fracturing fluid comprising a base fluid and at least onefracturing fluid component; introducing the fracturing fluid into asubterranean formation at a pressure sufficient to create or enhance atleast one fracture therein, thereby performing a fracturing operation inthe subterranean formation; and monitoring a characteristic of thefracturing fluid or a formation fluid using at least a firstopticoanalytical device within the subterranean formation, during a flowback of the fracturing fluid produced from the subterranean formation,or both.

In one embodiment, the present invention provides a method comprising:providing a fracturing fluid comprising a base fluid and at least onefracturing fluid component; introducing the fracturing fluid into asubterranean formation at a pressure sufficient to create or enhance atleast one fracture therein; and monitoring a characteristic of thefracturing fluid using at least a first opticoanalytical device that isin optical communication with a flow pathway for transporting thefracturing fluid before the fracturing fluid is introduced into thesubterranean formation.

In one embodiment, the present invention provides a method comprising:providing water from a water source; monitoring a characteristic of thewater using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the water; andintroducing the water into a subterranean formation.

In one embodiment, the present invention provides a method comprising:producing water from a first subterranean formation, thereby forming aproduced water; monitoring a characteristic of the produced water usinga first opticoanalytical device that is in optical communication with aflow pathway for transporting the produced water; forming a treatmentfluid comprising the produced water and at least one additionalcomponent; and introducing the treatment fluid into the firstsubterranean formation or a second subterranean formation.

In one embodiment, the present invention provides a method comprising:providing water from a water source; monitoring a characteristic of thewater using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the water; andtreating the water so as to alter at least one property thereof inresponse to the characteristic of the water monitored using the firstopticoanalytical device.

In one embodiment, the present invention provides a method comprising:providing a fluid in a fluid stream; and monitoring a characteristic ofthe fluid using a first opticoanalytical device that is in opticalcommunication with the fluid in the fluid stream.

In one embodiment, the present invention provides a method comprising:providing a fluid in a fluid stream; monitoring a characteristic of thefluid using a first opticoanalytical device that is in opticalcommunication with the fluid in the fluid stream; determining if thecharacteristic of the fluid needs to be adjusted based upon an outputfrom the first opticoanalytical device; performing an action on thefluid in the fluid stream so as to adjust the characteristic thereof;and after performing the action on the fluid in the fluid stream,monitoring the characteristic of the fluid using a secondopticoanalytical device that is in optical communication with the fluidin the fluid stream.

In one embodiment, the present invention provides a method comprising:providing water in a fluid stream; performing an action on the water inthe fluid stream so as to adjust a characteristic of the water; afterperforming the action on the water in the fluid stream, monitoring thecharacteristic of the water using an opticoanalytical device that is inoptical communication with the water in the fluid stream; anddetermining if the characteristic of the water lies within a desiredrange.

In one embodiment, the present invention provides a method comprising:monitoring live bacteria in water using a first opticoanalytical devicethat is in optical communication with the water.

In one embodiment, the present invention provides a method comprising:providing a treatment fluid comprising a base fluid and at least oneadditional component; monitoring live bacteria in the treatment fluidusing at least a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the treatment fluid;and introducing the treatment fluid into a subterranean formation, aftermonitoring the live bacteria therein.

In one embodiment, the present invention provides a method comprising:providing a treatment fluid comprising a base fluid and at least oneadditional component; introducing the treatment fluid into asubterranean formation; and monitoring live bacteria in the treatmentfluid within the subterranean formation using an opticoanalytical devicelocated therein.

The features and advantages of the present invention will be readilyapparent to one having ordinary skill in the art upon a reading of thedescription of the preferred embodiments that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of thepresent invention, and should not be viewed as exclusive embodiments.The subject matter disclosed is capable of considerable modification,alteration, and equivalents in form and function, as will occur to onehaving ordinary skill in the art and having the benefit of thisdisclosure.

FIG. 1 shows a block diagram non-mechanistically illustrating how anoptical computing device separates electromagnetic radiation related toa characteristic or analyte of interest from other electromagneticradiation.

FIG. 2 shows a non-limiting global schematic illustrating whereopticoanalytical devices (D) can be used in monitoring the process offorming a fluid, introducing a fluid into a subterranean formation, andproducing a fluid from a subterranean formation.

FIG. 3 shows an illustrative schematic demonstrating how an opticalcomputing device can be implemented along a flow pathway used fortransporting a fluid.

DETAILED DESCRIPTION

The present invention generally relates to methods for the monitoring offluids in or near real-time, and, more specifically, to methods formonitoring fluids prior to, during or after their introduction into asubterranean formation and/or to methods for monitoring produced fluidsfrom a subterranean formation.

Various embodiments described herein utilize opticoanalytical devicesthat can be utilized for the real-time or near real-time monitoring offluids that are ultimately introduced into a subterranean formation.Likewise, these opticoanalytical devices can be used to monitor fluidsthat are produced from a subterranean formation (including both flowback fluids, formation fluids, and combinations thereof) or to monitorand regulate fluids that are used in various processes. These devices,which are described in more detail herein, can advantageously provide ameasure of real-time or near real-time quality control over theintroduction of fluids into a subterranean formation that cannotpresently be achieved with either onsite analyses at a job site or moredetailed analyses that take place in a laboratory. Further, thesedevices can advantageously provide timely information regarding theeffectiveness of a treatment operation being performed in a subterraneanformation or the monitoring of a fluid in a fluid stream, particularlywhile the fluid stream is being modified in some way. A significantadvantage of these devices is that they can be configured tospecifically detect and/or measure a particular component of a fluid,thereby allowing qualitative and/or quantitative analyses of the fluidto occur without sample processing taking place. The ability to performquantitative analyses in real-time or near real-time represents adistinct advantage over time-consuming laboratory analyses, which caneither delay the start of a subterranean operation or provideinformation too late to proactively guide the performance of asubterranean operation. In addition, the opticoanalytical devices can becapable of monitoring a treatment operation while a treatment fluidresides within a subterranean formation.

The opticoanalytical devices utilized in the embodiments describedherein can advantageously allow at least some measure of proactive orresponsive control over a treatment operation or other type of operationusing a fluid to take place. In this regard, the capability of real-timeor near real-time monitoring using the opticoanalytical devices canadvantageously allow automation of a treatment operation to take placethrough an active feedback of information obtained using theopticoanalytical devices. Specifically, by coupling the opticoanalyticaldevice to a processor configured for manipulating analytical dataobtained therefrom (e.g., a computer, an artificial neural network,and/or the like), a treatment operation can be proactively controlled toallow a more effective treatment operation to take place. In some cases,the analytical data obtained from the opticoanalytical device can bemanipulated to determine ways in which a fluid can be modified toproduce or enhance a desired characteristic.

In addition, real-time or near real-dine monitoring usingopticoanalytical devices according to the embodiments described hereincan enable the collection and archival of fluid information inconjunction with operational information to optimize subsequentsubterranean operations in the same formation or in a differentformation having similar chemical and physical characteristics.Significantly, real-time or near real-time monitoring usingopticoanalytical devices can enhance the capacity for remote jobexecution.

The opticoanalytical devices suitable fix use in the present embodimentscan be deployed at any of a number of various points throughout a systemfor performing a treatment operation in a subterranean formation.Depending on the point(s) at which a treatment operation is monitoredusing the opticoanalytical device(s), various types of information aboutthe treatment operation can be obtained. For example, in some cases,quality control information regarding source materials and treatmentfluids formed therefrom can be obtained. In some cases, the change in atreatment fluid before and after introduction into a subterraneanformation can be obtained. In addition, the opticoanalytical devices ofthe present embodiments can be used to monitor a treatment fluid of aformation fluid while it is downhole and subject to conditions of thesubterranean environment, where it can potentially interact with thesurface of a subterranean formation. Still further, the opticoanalyticaldevices can be used to monitor a fluid being produced from asubterranean formation. Characterization of the produced fluid canprovide information about the effectiveness of a treatment operationthat has taken place. In addition, characterization of the producedfluid can more readily allow disposal or recycling of the fluid to takeplace, if that is desired. It is to be recognized that the foregoinglisting of information that can be obtained using opticoanalyticaldevices to monitor and/or control a treatment and/or production processshould be considered illustrative in nature only. Depending on thelocations of the opticoanalytical devices and the processing ofinformation obtained therefrom, other types of information can beobtained as well.

Even more generally, the opticoanalytical devices can be used to monitorfluids and various changes thereto according to the embodimentsdescribed herein. In some cases, the opticoanalytical devices can beused to monitor changes to a fluid that take place over time, forexample, in a pipeline or storage vessel. In some cases, theopticoanalytical devices can be used to monitor changes to a fluid thattake place as a result of performing an action on the fluid (e.g.,adding a component thereto, removing a component therefrom, or exposingthe fluid to a condition that potentially changes a characteristic ofthe fluid in some way). Thus, the opticoanalytical devices can be usedto monitor processes that take place upon fluids and in which fluids areused to gain an additional measure of process control.

As used herein, the term “fluid” refers to a substance that is capableof flowing, including particulate solids, liquids, and gases. In someembodiments, the fluid can be an aqueous fluid, including water. In someembodiments, the fluid can be a non-aqueous fluid, including organiccompounds, more specifically, hydrocarbons, oil, a refined component ofoil, petrochemical products, and the like. In some embodiments, thefluid can be a treatment fluid or a formation fluid. Fluids can includevarious flowable mixtures of solids, liquid and/or gases. Illustrativegases that can be considered fluids according to the present embodimentsinclude, for example, air, nitrogen, carbon dioxide, argon, methane andother hydrocarbon gases, and/or the like.

As used herein, the term “treatment fluid” refers to a fluid that isplaced in a subterranean formation in order to perform a desiredfunction. Treatment fluids can be used in a variety of subterraneanoperations, including, but not limited to, drilling operations,production treatments, stimulation treatments, remedial treatments,fluid diversion operations, fracturing operations, and the like. As usedherein, the terms “treatment” and “treating,” as they refer tosubterranean operations, refer to any subterranean operation that uses afluid in conjunction with performing a desired function and/or achievinga desired purpose. The terms “treatment” and “treating,” as used herein,do not imply any particular action by the fluid or any particularcomponent thereof unless otherwise specified. Treatment fluids caninclude, for example, drilling fluids, fracturing fluids, acidizingfluids, conformance treatment fluids, diverting fluids, damage controlfluids, remediation fluids, scale removal and inhibition fluids,chemical floods, sand control fluids, and the like. Generally, anytreatment fluid and any treatment operation can be monitored accordingto the general techniques described herein.

As used herein, the term “characteristic” refers to a chemical orphysical property of a substance. Illustrative characteristics of asubstance that can be monitored according to the methods describedherein can include, for example, chemical composition (identity andconcentration, in total or of individual components), impurity content,pH, viscosity, density, ionic strength, total dissolved solids, saltcontent, porosity, opacity, bacteria content, and the like.

As used herein, the term “electromagnetic radiation” refers to radiowaves, microwave radiation, infrared and near-infrared radiation,visible light, ultraviolet light, X-ray radiation and gamma rayradiation.

As used herein, the term “in-process” refers to an event that takesplace while a treatment fluid is being introduced into a subterraneanformation to perform a treatment operation, while the treatmentoperation is occurring, or while a flow back fluid is being producedfrom the subterranean formation as a result of the treatment operation.

As used herein, the term “flow back fluid” refers to a treatment fluidthat is produced from a subterranean formation subsequent to a treatmentoperation.

As used herein, the term “produced fluid” refers to a fluid that isobtained from a subterranean formation. A produced fluid can include aflow back fluid, a native formation fluid present in the subterraneanformation (including formation water or oil), or a combination thereof.

As used herein, the term “formation fluid” refers to a fluid that isnatively present in a subterranean formation.

As used herein, the term “in-line” refers to an event that takes placeduring a process without the process being substantially disrupted.

As used herein, the term “opticoanalytical device” refers to an opticaldevice that is operable to receive an input of electromagnetic radiationfrom a substance and produce an output of electromagnetic radiation froma processing element that is changed in some way so as to be readable bya detector, such that an output of the detector can be correlated to atleast one characteristic of the substance. The output of electromagneticradiation from the processing element can be reflected electromagneticradiation and/or transmitted electromagnetic radiation, and whetherreflected or transmitted electromagnetic radiation is analyzed by thedetector will be a matter of routine experimental design. In addition,fluorescent emission of the substance can also be monitored by theoptical devices.

As used herein, the term “flow pathway” refers to a route through whicha fluid is capable of being transported between two points. Flowpathways between two points need not necessarily be continuous.Illustrative flow pathways can include, various transportation meanssuch as, for example, pipelines, hoses, tankers, railway tank cars,barges, ships, and the like. In addition, the term flow pathway shouldnot be construed to mean that a fluid therein is flowing, rather that afluid therein is capable of being transported through flowing.

As used herein, the term “fluid stream” refers to quantity of fluid thatis flowing, for example, in a hose, pipeline or spray.

As used herein, the term “kill ratio” refers to the number of livebacteria present in a sample after a bactericidal treatment relative tothe number of live bacteria present in a sample before a bactericidaltreatment.

As used herein, the term “live bacteria” refers to bacteria that arecapable of metabolic activity and normal reproduction. In some cases,live bacteria can be metabolically inactive and not in a state of normalreproduction due to exposure to certain environmental conditions (e.g.,temperature or lack of an appropriate nutrient source), while stillretaining the capability for normal metabolic activity and reproductionupon exposure to more favorable environmental conditions. In someembodiments, live bacteria can be part of a population of bacteria thathas been substantially unaffected by a bactericidal treatment. Morespecifically, the term “live bacteria” refers to bacteria whose DNA orRNA has not been modified or degraded by a bactericidal treatment orwhose cell wall structure has not been modified or degraded by abactericidal treatment.

Opticoanalytical Devices

In general, opticoanalytical devices suitable for use in the presentembodiments can contain a processing element and a detector. In someembodiments, the opticoanalytical devices can be configured forspecifically detecting and analyzing a characteristic or substance ofinterest. In some embodiments, the opticoanalytical devices can beconfigured to quantitatively measure a characteristic or a substance ofinterest. In other embodiments, the opticoanalytical devices can begeneral purpose optical devices, with post-acquisition processing (e.g.,through computer means) being used to specifically detect acharacteristic or substance of interest.

In some embodiments, suitable opticoanalytical devices can be an opticalcomputing device. Suitable optical computing devices are described incommonly owned U.S. Pat. Nos. 6,198,531; 6,529,276; 7,123,844;7,834,999; 7,911,605, and 7,920,258, each of which is incorporatedherein by reference in its entirety, and U.S. patent application Ser.Nos. 12/094,460 (U.S. Patent Application Publication 2009/0219538),12/094,465 (U.S. Patent Application Publication 2009/0219539), and12/094,469 (U.S. Patent Application Publication 2009/0073433), each ofwhich is also incorporated herein by reference in its entirety.Accordingly, these optical computing devices will only be described inbrief herein. Other types of optical computing devices can also besuitable in alternative embodiments, and the foregoing optical computingdevices should not be considered to be limiting.

Optical computing devices described in the foregoing patents and patentapplications combine the advantage of the power, precision and accuracyassociated with laboratory spectrometers, while being extremely ruggedand suitable for field use. Furthermore, the optical computing devicescan perform calculations (analyses) in real-time or near real-timewithout the need for sample processing. In this regard, the opticalcomputing devices can be specifically configured (trained) to detect andanalyze particular characteristics and/or substances (analytes) ofinterest by using samples having known compositions and/orcharacteristics. As a result, interfering signals can be discriminatedfrom those of interest in a sample by appropriate configuration of theoptical computing devices, such that the optical computing devices canprovide a rapid response regarding the characteristics of a substancebased on the detected output. In some embodiments, the detected outputcan be converted into a voltage that is distinctive of the magnitude ofa characteristic being monitored in the sample. The foregoing advantagesand others make the optical computing devices particularly well suitedfor field and downhole use.

Unlike conventional spectrometers, the optical computing devices can beconfigured to detect not only the composition and concentrations of amaterial or mixture of materials, but they also can be configured todetermine physical properties and other characteristics of the materialas well, based on their analysis of the electromagnetic radiationreceived from the sample. For example, the optical computing devices canbe configured to determine the concentration of an analyte and correlatethe determined concentration to a characteristic of a substance by usingsuitable processing means. The optical computing devices can beconfigured to detect as many characteristics or analytes as desired in asample. All that is required to accomplish the monitoring of multiplecharacteristics or analytes is the incorporation of suitable processingand detection means within the optical computing device or eachcharacteristic or analyte. The properties of a substance can be acombination of the properties of the analytes therein (e.g., a linearcombination). Accordingly, the more characteristics and analytes thatare detected and analyzed using the optical computing device, the moreaccurately the properties of a substance can be determined.

Fundamentally, optical computing devices utilize electromagneticradiation to perform calculations, as opposed to the hardwired circuitsof conventional electronic processors. When electromagnetic radiationinteracts with a substance, unique physical and chemical informationabout the substance are encoded in the electromagnetic radiation that isreflected from, transmitted through or radiated from the sample. Thisinformation is often referred to as the substance's spectral“fingerprint.” The optical computing devices utilized herein are capableof extracting the information of the spectral fingerprint of multiplecharacteristics or analytes within a substance and converting thatinformation into a detectable output regarding the overall properties ofa sample. That is, through suitable configuration of the opticalcomputing devices, electromagnetic radiation associated withcharacteristics or analytes of interest in a substance can be separatedfrom electromagnetic radiation associated with all other components of asample in order to estimate the sample's properties in real-time or nearreal-time.

In various embodiments, the optical computing devices can contain anintegrated computational element (ICE) that is capable of separatingelectromagnetic radiation related to the characteristic or analyte ofinterest from electromagnetic radiation related to other components of asample. Further details regarding how the optical computing devices canseparate and process electromagnetic radiation related to thecharacteristic or analyte of interest are described in U.S. Pat. No.7,920,258, previously incorporated herein by reference. FIG. 1 shows ablock diagram non-mechanistically illustrating how an optical computingdevice separates electromagnetic radiation related to a characteristicor analyte of interest from other electromagnetic radiation. As shown inFIG. 1, after being illuminated with incident electromagnetic radiation,sample 100 containing an analyte of interest produces an output ofelectromagnetic radiation, some of which is electromagnetic radiation101 from the characteristic or analyte of interest and some of which isbackground electromagnetic radiation 101′ from other components ofsample 100. Electromagnetic radiation 101 and 101′ impinge upon opticalcomputing device 102, which contains ICE 103 therein. ICE 103 separateselectromagnetic radiation 101 from electromagnetic radiation 101′.Transmitted electromagnetic radiation 105, which is related to thecharacteristic or analyte of interest, is carried to detector 106 foranalysis and quantification (e.g., to produce an output of thecharacteristics of sample 100). Reflected electromagnetic radiation 104,which is related to other components of sample 100, can be directed awayfrom detector 106. In alternative configurations of optical computingdevice 102, reflected electromagnetic radiation 104 can be related tothe analyte of interest, and transmitted electromagnetic radiation 105can be related to other components of the sample. In some embodiments, asecond detector (not shown) can be present that detects theelectromagnetic radiation reflected from ICE 103. Without limitation,the output of the second detector can be used to normalize the output ofdetector 106. In some embodiments, a beam splitter can be employed (notshown) to split the two optical beams, and the transmitted or reflectedelectromagnetic radiation can then directed to ICE 103. That is, in suchembodiments, ICE 103 does not function as the beam splitter, as depictedin FIG. 1, and the transmitted or reflected electromagnetic radiationsimply passes through ICE 103, being computationally processed therein,before travelling to detector 106.

Suitable ICE components are described in commonly owned U.S. Pat. Nos.6,198,531; 6,529,276; and 7,911,605, each previously incorporated hereinby reference, and in Myrick, et al. “Spectral tolerance determinationfor multivariate optical element design,” FRESENUIS' JOURNAL OFANALYTICAL CHEMISTRY, 369:2001, pp. 351-355, which is also incorporatedherein by reference in its entirety. In general, an ICE comprises anoptical element whose transmissive, reflective, and/or absorptiveproperties are suitable for detection of a characteristic or analyte ofinterest. The optical element can contain a specific material foraccomplishing this purpose (e.g., silicon, germanium, water, or othermaterial of interest). In some embodiments, the material can be doped ortwo or more materials can be combined in a manner to result in thedesired optical characteristic. For example, deposited layers ofmaterials that have appropriate concentrations and thicknesses can beused to create an ICE having suitable properties. In addition to solids,an ICE can also contain liquids and/or gases, optionally in combinationwith solids, in order to produce a desired optical characteristic. Inthe case of gases and liquids, the ICE can contain a vessel which housesthe gases or liquids. In addition to the foregoing, an ICE can alsocomprise holographic optical elements, gratings, and/or acousto-opticelements, for example, that can create transmission, reflection, and/orabsorptive properties of interest. Other types of ICE components canalso be suitable in alternative embodiments, and the foregoing ICEcomponents should not be considered to be limiting.

Once ICE 103 has separated electromagnetic radiation 101 related to thesample, optical computing device 102 can provide an optical signal(e.g., transmitted electromagnetic radiation 105), which is related tothe amount (e.g., concentration) of the characteristic or analyte ofinterest. In some embodiments, the relation between the optical signaland the concentration can be a direct proportion. Detector 106 can beconfigured to detect transmitted electromagnetic radiation 105 andproduce voltage output in an embodiment, which is related to the amountof the characteristic or analyte of interest.

When monitoring more than one analyte at a time, various configurationsfor multiple ICEs can be used, where each ICE has been configured todetect a particular characteristic or analyte of interest. In someembodiments, the characteristic or analyte can be analyzed sequentiallyusing multiple ICEs that are presented to a single beam ofelectromagnetic radiation being reflected from or transmitted through asample. In some embodiments, multiple ICEs can be located on a rotatingdisc, where the individual ICEs are only exposed to the beam ofelectromagnetic radiation for a short time. Advantages of this approachcan include the ability to analyze multiple analytes using a singleoptical computing device and the opportunity to assay additionalanalytes simply by adding additional ICEs to the rotating disc. Invarious embodiments, the rotating disc can be turned at a frequency ofabout 10 RPM to about 30,000 RPM such that each analyte in a sample ismeasured rapidly. In some embodiments, these values can be averaged overan appropriate time domain (e.g., about 1 millisecond to about 1 hour)to more accurately determine the sample characteristics.

In other embodiments, multiple optical computing devices can be placedparallel, where each optical computing device contains a unique ICE thatis configured to detect a particular characteristic or analyte ofinterest. In such embodiments, abeam splitter can divert a portion ofthe electromagnetic radiation being reflected by, emitted from ortransmitted through from the substance being analyzed into each opticalcomputing device. Each optical computing device, in turn, can be coupledto a detector or detector array that is configured to detect and analyzean output of electromagnetic radiation from the optical computingdevice. Parallel configurations of optical computing devices can beparticularly beneficial for applications that require low power inputsand/or no moving parts.

In still additional embodiments, multiple optical computing devices canbe placed in series, such that characteristics or analytes are measuredsequentially at different locations and times. For example, in someembodiments, a characteristic or analyte can be measured in a firstlocation using a first optical computing device, and the characteristicor analyte can be measured in a second location using a second opticalcomputing device. In other embodiments, a first characteristic oranalyte can be measured in a first location using a first opticalcomputing device, and a second characteristic or analyte can be measuredin a second location using a second optical computing device. It shouldalso be recognized that any of the foregoing configurations for theoptical computing devices can be used in combination with a seriesconfiguration in any of the present embodiments. For example, twooptical computing devices having a rotating disc with a plurality ofICEs thereon can be placed in series for performing an analysis.Likewise, multiple detection stations, each containing optical computingdevices in parallel, can be placed in series for performing an analysis.

In alternative embodiments, a suitable opticoanalytical device can be aspectrometer than has been ruggedized for field use. In variousembodiments, a suitable spectrometer can include, for example, aninfrared spectrometer, a UV/VIS spectrometer, a Raman spectrometer, amicrowave spectrometer, a fluorescence spectrometer, and the like. It isto be recognized that any of the preferred embodiments described hereinusing an optical computing device can be practiced in a like mannerusing a spectrometer, which in most cases has been ruggedized for fielduse. Techniques for ruggedizing the foregoing spectrometers will bedependent upon the field conditions in which measurements are to takeplace. Suitable ruggedization techniques will be apparent to one havingordinary skill in the art.

Automated Control and Remote Operation

In some embodiments, the characteristics of the sample being analyzedusing the opticoanalytical device can be further processedcomputationally to provide additional characterization information aboutthe substance being analyzed. In some embodiments, the identificationand concentration of each analyte in a sample can be used to predictcertain physical characteristics of the sample. For example, the bulkcharacteristics of a sample can be estimated by using a combination ofthe properties conferred to the sample by each analyte.

In some embodiments, the concentration of each analyte or the magnitudeof each characteristic determined using the opticoanalytical devices canbe fed into an algorithm operating under computer control. In someembodiments, this algorithm can make predictions on how thecharacteristics of the sample change if the concentrations of theanalytes are changed relative to one another. In some embodiments, thealgorithm can be linked to any step of the process for introducing afluid or producing a fluid from a subterranean formation so as to changethe characteristics of the fluid being introduced to or produced from asubterranean formation. In more general embodiments, the algorithm canbe linked to a fluid being modified by some process, such that the fluidcan be monitored in-process. In some embodiments, the algorithm cansimply produce an output that is readable by an operator, and theoperator can manually take appropriate action based upon the output. Forexample, if the algorithm determines that a component of a treatmentfluid being introduced into a subterranean formation is out of range,the operator can direct that additional amounts of the component beadded to the treatment fluid “on-the-fly.” In some embodiments, onsitemonitoring control by the operator can take place, while in otherembodiments the operator can be offsite white controlling the processremotely through suitable communication means. In some embodiments, thealgorithm can take proactive process control by automatically adjustingthe characteristics of a treatment fluid being introduced into asubterranean formation or by halting the introduction of the treatmentfluid in response to an out of range condition. For example, thealgorithm can be configured such that if a component of interest is outof range, the amount of the component can be automatically increased ordecreased in response. In some embodiments, the response to the out ofrange condition can involve the addition of a component that is notalready in the treatment fluid. Likewise, if an inappropriate analyte isdetected in a fluid to be introduced into a subterranean formation, thealgorithm can determine a corrective action (e.g., a component to beadded) to counteract or remove the characteristics conferred by thatanalyte.

In some embodiments, the algorithm can be part of an artificial neuralnetwork. In some embodiments, the artificial neural network can use theconcentration of each detected analyte in order to evaluate thecharacteristics of the sample and predict how to modify the sample inorder to alter its properties in a desired way. Illustrative butnon-limiting artificial neural networks are described in commonly ownedU.S. patent application Ser. No. 11/986,763 (U.S. Patent ApplicationPublication 2009/0182693), which is incorporated herein by reference inits entirety. For example, in a fluid containing two analytes ofinterest, a simple algorithm-based approach might detect that theconcentrations of both analytes are out of range and adjust thecomposition of the fluid to bring the analytes back in range. However,an adjustment using an artificial neural network might determine thateven though both analytes are out of range, the detected amounts, incombination, maintain a bulk characteristic of the fluid within adesired range. For example, an algorithm-based approach might determinethat both a gelling agent concentration and ionic strength are out oftheir specified range for a fluid and mandate adjustment thereof;however, an artificial neural network might determine that the analyzedconcentrations, in combination, are sufficient for maintaining a desiredviscosity within the fluid and not direct that adjustment be made. Anycombination of analytes and properties determined thereby lie within thespirit and scope of the present invention.

It is to be recognized that an artificial neural network can be trainedusing samples having known concentrations, compositions and properties.As the training set of information available to the artificial neuralnetwork becomes larger, the neural network can become more capable ofaccurately predicting the characteristics of a sample having any numberof analytes present therein. Furthermore, with sufficient training, theartificial neural network can more accurately predict thecharacteristics of the sample, even in the presence of unknown analytes.

It is to be recognized that in the various embodiments herein directedto computer control and artificial neural networks that various blocks,modules, elements, components, methods and algorithms can be implementedthrough using computer hardware, software and combinations thereof. Toillustrate this interchangeability of hardware and software, variousillustrative blocks, modules, elements, components, methods andalgorithms have been described generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware will depend upon the particular application and any imposeddesign constraints. For at least this reason, it is to be recognizedthat one of ordinary skill in the art can implement the describedfunctionality in a variety of ways for a particular application.Further, various components and blocks can be arranged in a differentorder or partitioned differently, for example, without departing fromthe spirit and scope of the embodiments expressly described.

Computer hardware used to implement the various illustrative blocks,modules, elements, components, methods and algorithms described hereincan include a processor configured to execute one or more sequences ofinstructions, programming or code stored on a readable medium. Theprocessor can be, for example, a general purpose microprocessor, amicrocontroller, a digital signal processor, an application specificintegrated circuit, a field programmable gate array, a programmablelogic device, a controller, a state machine, a gated logic, discretehardware components, an artificial neural network or any like suitableentity that can perform calculations or other manipulations of data. Insome embodiments, computer hardware can further include elements suchas, for example, a memory [e.g., random access memory (RAM), flashmemory, read only memory (ROM), programmable read only memory (PROM),erasable PROM], registers, hard disks, removable disks, CD-ROMS, DVDs,or any other like suitable storage device.

Executable sequences described herein can be implemented with one ormore sequences of code contained in a memory. In some embodiments, suchcode can be read into the memory from another machine-readable medium.Execution of the sequences of instructions contained in the memory cancause a processor to perform the process steps described herein. One ormore processors in a multi-processing arrangement can also be employedto execute instruction sequences in the memory. In addition, hard-wiredcircuitry can be used in place of or in combination with softwareinstructions to implement various embodiments described herein. Thus,the present embodiments are not limited to any specific combination ofhardware and software.

As used herein, a machine-readable medium will refer to any medium thatdirectly or indirectly provides instructions to a processor forexecution. A machine-readable medium can take on many forms including,for example, non-volatile media, volatile media, and transmission media.Non-volatile media can include, for example, optical and magnetic disks.Volatile media can include, for example, dynamic memory. Transmissionmedia can include, for example, coaxial cables, wire, fiber optics, andwires that form a bus. Common forms of machine-readable media caninclude, for example, floppy disks, flexible disks, hard disks, magnetictapes, other like magnetic media, CD-ROMs, DVDs, other like opticalmedia, punch cards, paper tapes and like physical media with patternedholes, RAM, ROM, PROM, EPROM and flash EPROM.

In some embodiments, the data collected using the opticoanalyticaldevices can be archived along with data associated with operationalparameters being logged at a job site. Evaluation of job performance canthen be assessed and improved for future operations or such informationcan be used to design subsequent operations. In addition, the data andinformation can be communicated to a remote location by a communicationsystem (e.g., satellite communication or wide area networkcommunication) for further analysis. The communication system can alsoallow remote monitoring and operation of a process to take place.Automated control with a long-range communication system can furtherfacilitate the performance of remote job operations. In particular, anartificial neural network can be used in some embodiments to facilitatethe performance of remote job operations. That is, remote job operationscan be conducted automatically in some embodiments. In otherembodiments, however, remote job operations can occur under directoperator control, where the operator is not at the job site.

Location of the Opticoanalytical Devices

FIG. 2 shows a non-limiting global schematic illustrating whereopticoanalytical devices (D), according to some embodiments of thepresent invention, can be used in monitoring the process of forming afluid, introducing a fluid into a subterranean formation, and producinga fluid from a subterranean formation. It is to be recognized that theplacement of opticoanalytical devices (D) depicted in FIG. 2 should beconsidered illustrative in nature only for purposes of describingexemplary flow pathways used in forming and using fluids. As illustratedin FIG. 2, the recovery of a flow back fluid from a subterraneanformation is also included and considered to be a part of the normalflow pathways for forming and using a fluid, according to the presentembodiments. FIG. 2 depicts potential monitoring locations along anillustrative flow pathway used for forming a fluid, whereopticoanalytical devices (D) can be used to monitor variouscharacteristics of the fluid. The monitoring locations are optional, andpotentially additive, based on the needs of a user. Depending on theuser's needs, an opticoanalytical (D) device at one location can beused, or opticoanalytical devices (D) at multiple locations can be usedin any combination that is suitable to the user. For example, in aparticular implementation of a fluid formation, introduction andproduction process, it is anticipated that only some of theopticoanalytical devices (D) will be present, but this will be a matterof operational design for a user depending upon the level of monitoringand information needed by the user. Moreover, opticoanalytical devices(D) can be at locations other than those depicted in FIG. 2, and/ormultiple opticoanalytical devices (D) can be placed at each depictedlocation or others. Without limitation, in some embodiments, theopticoanalytical devices (D) can be used in at least the followinglocations for monitoring a fluid being formed or introducedinto/produced from a subterranean formation: at a supplier for acomponent of the fluid, on a transport means for the component, at afield site upon receipt of the component, at a storage site for thecomponent, prior to and after combining one or more components to form atreatment fluid, during transport to and just before introduction into asubterranean formation, within a subterranean formation, and in the flowback fluid produced from the subterranean formation. Information thatcan be obtained at each of these locations, including process controlresulting therefrom, will now be described in more detail.

Sourcing and Transport

Referring to FIG. 2, source material 200 can be monitored with anopticoanalytical device (D1) prior or during transfer of a material totransport means 201. In some embodiments, opticoanalytical device (D1)can be located at the exit of a container housing source material 200.In other embodiments, opticoanalytical device (D1) can be located in atank or storage vessel housing source material 200, in still otherembodiments, opticoanalytical device (D1) can be located on transportmeans 201.

Analyses that can be obtained at this stage include, without limitation,the identity, concentration and purity of source material 200. That is,opticoanalytical device (D1) can be used as an initial quality check toensure that the proper source material has been obtained. The sourcematerial on transport means 201 can then be transported to storage areas202, 202′ and 202″ at a job site. Although FIG. 2 has depicted a singletransport means 201 delivering the same source material to storage areas202, 202′ and 202″, it is to be recognized that in most cases storageareas 202, 202′ and 202″ will each contain different materials that aretransported by separate transport means 201. Further, it is to berecognized that any number of source materials can be utilized in theprocesses described herein. That is, the depiction of only three storageareas should not be considered limiting. Prior to depositing the sourcematerial in transport means 201 in any of storage areas 202, 202′ or202″, opticoanalytical devices (D2-D4) can again be used to verify thatthe source material in transport means 201 has been delivered to theproper storage area and to verify that the source material has notdegraded or otherwise changed during transport. It is to be furtherrecognized that storage at a job site can optionally be omitted and thesource material on transport means 201 can be directly combined withother materials to make a treatment fluid. Production of treatmentfluids and monitoring thereof is discussed in greater detailhereinafter.

In the field of subterranean operations, source material 200 is mostoften obtained from a supplier at a location that is remote from a jobsite. Accordingly, transport means 201 is most typically a mobilecarrier such as, for example, a truck, a railway car, boat or a barge.In FIG. 2, the lines connecting source material 200, transport means 201and storage areas 202, 202′ and 202″ are broken to indicate that thereis no fixed pathway therebetween. Although not typical in the field ofsubterranean operations, transport means 201 can alternately be a fixedpathway, such as a pipeline, for example, in alternative embodiments.

In addition, once the source material is in storage areas 202, 202′and/or 202″, the source material can also be monitored withopticoanalytical devices (not shown) located within each storage area.The opticoanalytical devices within storage areas 202, 202′ and/or 202″can be used, for example, to determine if the source material degradesor is otherwise changed during storage. Further, analysis of the sourcematerial while in storage areas 202, 202′ and/or 202″ can be utilized byan operator to determine the quantities of source material to be used ina treatment fluid for subterranean operations.

Combining Source Materials to Make a Treatment Fluid

After obtaining one or more source materials at a job site, in someembodiments, combining of the source materials to make a treatment fluidcan then take place. It is to be understood that the term “combining”does not imply any particular action for combining (e.g., mixing orhomogenizing) or degree of combining unless otherwise noted. Referringagain to FIG. 2, the source materials in storage areas 202, 202′ and202″ can be combined with a base fluid in vessel 204 in order to form atreatment fluid therein. The source materials being transported fromstorage areas 202, 202′ and 202″ can again be monitored withopticoanalytical devices (D5-D7) prior to being introduced into vessel204 to ensure that the proper source materials are present and that theyhave not degraded or otherwise changed during storage. Likewise, thecharacteristics of the base fluid from base fluid source 203 can bemonitored using opticoanalytical device (D8). As discussed hereinafter,the base fluid can alternately be obtained from recycled fluid stream212, as discussed in more detail hereinbelow. In either case, monitoringof the base fluid can be important to ensure that a treatment fluidhaving the desired characteristics is formed.

It is to be recognized that vessel 204 can take on many different forms,and the only requirement is that vessel 204 be suitable for combiningthe source material(s) with the base fluid. In some embodiments, vessel204 be a mixer, blender or homogenizer. In some embodiments, vessel 204can be a mixing tank. In some embodiments, vessel 204 can be a pipe. Instill other embodiments, vessel 204 can utilize an air mixer to combinethe source materials with a base fluid. In some embodiments, vessel 204can be a reaction chamber in which at least some of the source materialsreact with one another upon forming the treatment fluid.

In various embodiments, the base fluid can be an aqueous base fluid suchas, for example, fresh water, acidified water, salt water, seawater,brine, aqueous salt solutions, surface water (i.e., streams, rivers,ponds and lakes), underground water from an aquifer, municipal water,municipal waste water, or produced water (e.g., from recycled fluidstream 212) from a subterranean formation, in alternative embodiments,the base fluid can be a non-aqueous base fluid such as, for example, ahydrocarbon base fluid. As will be evident to one having ordinary skillin the art, some treatment operations can be ineffective if the basefluid contains certain trace materials that prevent an effectivetreatment operation from occurring. For example, fracturing operationscan be ineffective in the presence of certain ionic materials or somebacteria. Similarly, certain trace materials in a base fluid caninteract in an undesired fashion with a source material. For example, ifthe base fluid contains excess sulfate ions, a precipitate can form inthe presence of barium ions from a source material. According to thepresent embodiments, a base fluid containing incompatibilities can beidentified before the formation of a treatment fluid, thereby conservingvaluable resources that could otherwise be wasted in producing anineffective and potentially damaging treatment fluid.

It should again be noted that until vessel 204 is reached, thecharacteristics of the source material(s) and the base fluid aremonitored prior to their being combined with one another. Thus,incorrect source materials or out of range characteristics can bereadily identified and addressed according to the embodiments describedherein. For example, the composition of the treatment fluid can beadjusted in order to address an out of range condition. As previouslydescribed, monitoring and control of the process can take placeautomatically in order to address out of range conditions as soon aspossible.

Continuing now with FIG. 2, a treatment fluid formed in vessel 204 canbe monitored after its formation to verify that it has the desiredcharacteristics for performing a particular treatment operation.Monitoring can be performed using opticoanalytical device (D9) as thetreatment fluid exits vessel 204. Alternately, opticoanalytical device(D9) can monitor the treatment fluid while in vessel 204. Thereafter,the treatment fluid can be transported to pump 205 for introduction intosubterranean formation 2110. In the event that the treatment fluid hasnot been properly combined in vessel 204 or if its characteristics arenot those desired, the treatment fluid can be diverted back into vessel204 rather than being introduced into subterranean formation 210(diversion pathway not shown). For example, a treatment fluid that wasimproperly mixed in vessel 204 might have an incorrect composition orhave an out of range viscosity that can be remedied by continued mixing.Optionally, one or more additional source materials or the same sourcematerials added previously can be added to address the out of rangecondition. Further optionally, the treatment fluid can be disposed of ifits characteristics cannot be suitably altered by addition of one ormore additional substances or by continued mixing. Although not optimal,the disposal of a treatment fluid presents less serious economicconcerns than haphazardly introducing the treatment fluid downhole whereit can potentially damage a subterranean formation.

In some embodiments, the treatment fluid can be formed in vessel 204 ata job site and directly transferred to pump 205 via a pipeline or othertype of fixed transfer means. In some embodiments, the treatment fluidcan be formed in vessel 204 at a remote site and transferred via mobiletransfer means 206 where there is again not a fixed connection betweenvessel 204 and pump 205. The latter situation exists for offshoresubterranean operations, wherein a treatment fluid can be formed onshoreand transported via boat or barge to an offshore drilling platform forintroduction downhole. As with transfer means 201, the treatment fluidcan be monitored with opticoanalytical device (D10) as it is loaded onmobile transfer means 206 as a quality control check of the transferprocess.

In the case of a treatment fluid formed at a job site, the monitoring ofthe treatment fluid prior to introduction into pump 205 is not typicallyof great concern, since the connection pathway thereto is usually fixedand the lag time between formation of the treatment fluid and downholepumping is usually not lengthy. However, in the event that the treatmentfluid is stored in vessel 204 or elsewhere prior to being introduceddownhole, opticoanalytical device (D11) can be used to verify that thecharacteristics of the treatment fluid are still suitable for beingintroduced into the subterranean formation. Opticoanalytical device(D11) can be particularly useful for offshore subterranean operations.In the case of offshore subterranean operations, there can be asignificant delay between the formation of a treatment fluid anddownhole pumping, which can present the opportunity for degradation ofthe treatment fluid to occur. That is, a treatment fluid that wasinitially suitable, as measured by opticoanalytical device (D9), canchange significantly in characteristics by the time it reaches anoffshore site. In either case, the characteristics of the treatmentfluid can again be monitored using opticoanalytical device (D11) as afinal quality check before the treatment fluid is introduced intosubterranean formation 210. Further, the characteristics monitored usingopticoanalytical device (D11) can be used, in some embodiments, as abaseline value to help evaluate the effectiveness of a treatmentoperation, as discussed in more detail hereinafter.

If the characteristics of the treatment fluid being introduced intosubterranean formation 210 are not in the desired range, in someembodiments, the treatment operation can be stopped or thecharacteristics of the treatment fluid can be adjusted. In someembodiments, the treatment fluid can be returned to vessel 204 to adjustthe characteristics of the treatment fluid. In other embodiments, thetreatment operation can be continued, with one or more additionalcomponents being added at the well head while the treatment fluid isbeing introduced into the subterranean formation, referred to herein as“on-the-fly addition” (process not shown).

Monitoring a Treatment Operation and a Flow Back Fluid Produced from aSubterranean Formation

Once introduced into subterranean formation 210, in some embodiments,one or more opticoanalytical devices (D12) can be used to monitor thetreatment fluid while in the formation (e.g., in the well bore).Depending on the location(s) of the one or more opticoanalytical devices(D12) in subterranean formation 210 (e.g. in the well bore), varioustypes of information on the treatment operation can be determined inreal-time or near real-time based upon fluid flow into or out ofsubterranean formation 210. For example, in some embodiments, theconsumption of a substance in the treatment fluid can be monitored asthe treatment fluid passes through various subterranean zones. In otherembodiments, the flow pathway of the treatment fluid in the subterraneanformation can be monitored as it passes various opticoanalytical devices(D12). Information obtained from opticoanalytical devices (D12) can notonly be used to map the morphology of the subterranean formation butalso to indicate whether the characteristics of the treatment fluid needto be changed in order to perform a more effective treatment. Forexample, the treatment fluid can be modified in order to addressspecific conditions that are being encountered downhole. In addition, insome embodiments, the treatment fluid can be monitored to ensure thatits characteristics do not change in an undesirable way when introducedinto the downhole environment. In the event that the treatment fluidundesirably changes upon being introduced downhole, the treatment fluidbeing introduced into subterranean formation 210 can be modified, asdescribed above, or an additional component can be introduced separatelywithin subterranean formation 210 in order to address changes incharacteristics that occur during transit downhole. In some embodiments,a treatment fluid can be monitored downhole using opticoanalyticaldevices (D12) in order to evaluate fluid displacement and fluiddiversion in the subterranean formation (e.g., the flow pathway). Insuch embodiments, real-time or near-real time data from opticoanalyticaldevices (D12) can be used to adjust the placement of the fluid usingdiverting agents and to evaluate the effectiveness of diverting agents.In some embodiments, the diverting agents can be added to the treatmentfluid in response to the characteristics observed using opticoanalyticaldevices (D12). In other embodiments, fracture conductivity in thesubterranean formation can be monitored using the opticoanalyticaldevices. In still other embodiments, a formation fluid can be monitoredusing opticoanalytical devices (D12).

In addition to monitoring a treatment operation while the treatmentfluid is downhole, the flow back fluid produced from subterraneanformation 210 can be monitored using opticoanalytical device (D13) toprovide information on the treatment operation. It is to be noted thatmonitoring the flow back fluid is where one would conventionally monitorthe effectiveness of a treatment operation by collecting aliquots of theflow back fluid and conducting suitable laboratory analyses. In thepresent embodiments, the characteristics of the flow back fluid, asmonitored using opticoanalytical device (D13), can be compared to thecharacteristics of treatment fluid being introduced into subterraneanformation 210, as monitored using opticoanalytical device (D11). Anychanges in characteristics, or tack thereof, can be indicative of theeffectiveness of the treatment operation. For example, the total orpartial consumption of a component in the flow back fluid (e.g., viachemical reactions in the subterranean formation) or the formation of anew substance in the flow back fluid can be indicative that at leastsome treatment effect has occurred. In some embodiments, a change inconcentration of a component in the treatment fluid can be determined bymonitoring the concentration in the flow back fluid usingopticoanalytical device (D13) and the concentration of the componentprior to its introduction into subterranean formation 210 usingopticoanalytical device (D11) or another upstream opticoanalyticaldevice. In some embodiments, the change in concentration can becorrelated to an effectiveness of a treatment operation being performedin subterranean formation 210.

In some embodiments, the flow back fluid can comprise an aqueous basefluid that is produced from subterranean formation 210 as a result of atreatment operation. In other embodiments, the flow back fluid cancomprise a formation water that is produced from subterranean formation210, particularly as a result of a treatment operation. In still otherembodiments, the flow back fluid can also comprise a producedhydrocarbon from subterranean formation 210.

After analysis, flow back fluid stream 211 can be directed in at leasttwo different ways, some embodiments, the flow back fluid can beanalyzed and disposed of other embodiments, the flow back fluid can beanalyzed and recycled.

In some embodiments, if an initial analysis of the flow back fluid issatisfactory using opticoanalytical device (D13), flow back fluid stream211 can again be optionally analyzed with opticoanalytical device (D14)and sent to disposal stream 213, provided that the characteristics ofthe flow back fluid remain within acceptable disposal parameters. If theinitial analysis of the flow back fluid is not satisfactory fordisposal, as determined by opticoanalytical device (D13), flow backfluid stream 211 can have at least one additional substance addedthereto in order to adjust its characteristics and make it suitable fordisposal. For example, a flow back fluid that is too acidic can be atleast partially neutralized and analyzed again using opticoanalyticaldevice (D14) prior to disposal. Alternatively, flow hack fluid stream211 can have a substance removed therefrom in order to adjust itscharacteristics and make it suitable for disposal. For example, a metalcontaminant in flow back fluid stream 211 can be removed by ion exchangetechniques in an embodiment.

Preferably, flow back fluid stream 211 can be reused in subsequentsubterranean operations such as, for example, as the base fluid of atreatment fluid (e.g., a fracturing fluid) or in a water floodingoperation. In this regard, flow back fluid stream 211 can be monitoredusing opticoanalytical device (D15) and modified, if necessary, byadding at least one substance thereto or removing at least one substancetherefrom, to produce recycled fluid stream 212. After forming recycledfluid stream 212, it can be monitored using opticoanalytical device(D16) to verify that it has the characteristics for forming anothertreatment fluid in vessel 204. The treatment fluid formed using recycledfluid stream 212 can be used in subterranean formation 210, in someembodiments, or transported to another subterranean formation in otherembodiments. Alternately, recycled fluid stream 212 can be monitoredusing opticoanalytical device (D17) to ensure that it is suitable forbeing reintroduced into subterranean formation 210 or anothersubterranean formation. That is, in some embodiments, the flow backfluid produced from a first subterranean formation can be used in awater flooding operation in a second subterranean formation. It is to benoted that if no modification of flow back fluid stream 211 is needed,then formation of a treatment fluid or introduction into a subterraneanformation can take place without further modification occurring.

In other embodiments, opticoanalytical device (D13) can be used to assaya non-aqueous fluid being produced from a subterranean formation. Forexample, opticoanalytical device (D13) can be used to determine thecomposition of a formation fluid (e.g., a hydrocarbon) being producedfrom the subterranean formation.

Monitoring the Formation and Transport of a Treatment Fluid

In various embodiments, the methods described herein can be used tomonitor and control the formation and transport of any type of treatmentfluid intended for introduction into a subterranean formation.Regardless of the intended form or function of the treatment fluid, anydesired characteristic of the treatment fluid can be monitored accordingto some embodiments described herein. Without limitation, treatmentfluids that can be monitored during their formation and transportaccording to the present embodiments can include, for example,fracturing fluids, gravel packing fluids, acidizing fluids, conformancecontrol fluids, gelled fluids, fluids comprising a relative permeabilitymodifier, diverting fluids, fluids comprising a breaker, biocidaltreatment fluids, remediation fluids, and the like. Although severalspecific examples of treatment fluids are set forth hereinafter in whichthe present methods can be used for monitoring, it is to be recognizedthat these examples are illustrative in nature only, and other types oftreatment fluids can be monitored by one having ordinary skill in theart by employing like techniques.

Illustrative substances that can be present in any of the treatmentfluids of the present invention can include, for example, acids,acid-generating compounds, bases, base-generating compounds,surfactants, scale inhibitors, corrosion inhibitors, gelling agents,crosslinking agents, anti-sludging agents, foaming agents, defoamingagents, antifoam agents, emulsifying agents, dc-emulsifying agents, ironcontrol agents, proppants or other particulates, gravel, particulatediverters, salts, fluid loss control additives, gases, catalysts, claycontrol agents, chelating agents, corrosion inhibitors, dispersants,flocculants; scavengers (e.g., H₂S scavengers, CO₂ scavengers or O₂scavengers), lubricants, breakers, delayed release breakers, frictionreducers, bridging agents, viscosifiers, weighting agents, solubilizers,rheology control agents, viscosity modifiers, pH control agents (e.g.,buffers), hydrate inhibitors, relative permeability modifiers, divertingagents, consolidating agents, fibrous materials, bactericides, tracers,probes, nanoparticles, and the like. Combinations of these substancescan be used as well.

In various embodiments, the treatment fluids used in practicing thepresent invention also comprise a base fluid. In some embodiments, thebase fluid can be an aqueous base fluid, in other embodiments, the basefluid can be a non-aqueous base fluid, such as a hydrocarbon.

In various embodiments of the present invention, opticoanalyticaldevices (e.g., optical computing devices and ruggedized spectrometers)can be used to monitor a treatment fluid during its formation andtransport. Monitoring of source materials to be used in the treatmentfluid, including water, can also be performed by like techniques as aquality control measure. In some embodiments, monitoring of thetreatment fluid and the source material can occur “in-line” or“in-process” along a flow pathway for transporting the treatment fluidor source material without the transport being interrupted orsignificantly altered. For example, the embodiment shown in FIG. 2illustrates how an in-line process can be implemented in someembodiments, where the in-line monitoring can take place using at leastone opticoanalytical device that is in optical communication with theflow pathway. As used herein, the term “in optical communication” refersto the condition of an opticoanalytical device being positioned along aflow pathway and the flow pathway being configured such thatelectromagnetic radiation reflected from, emitted by or transmittedthrough a fluid in the flow pathway is readable by the opticoanalyticaldevice. FIG. 3, which is discussed in more detail hereinbelow, shows anembodiment in which an opticoanalytical device can be in opticalcommunication with a flow pathway. In some embodiments, monitoring afluid along a flow pathway (e.g., in a line) using an opticoanalyticaldevice can take place white the fluid is flowing without the fluidtransport process being interrupted. In other embodiments, monitoring afluid along a flow pathway can take place without the fluid beingtransported. That is, the fluid transport process can be temporarilyinterrupted while monitoring takes place, with the fluid remainingsubstantially static in the flow pathway during monitoring. In stillother embodiments, the flow pathway can be configured to divert aportion of the fluid away from its main transport pathway, wheremonitoring of the fluid can take place using the diverted portion. Inalternative embodiments, the fluid from the diverted portion can beremoved from the system and analyzed using an opticoanalytical device ata job site, where the opticoanalytical device is not used in-process.That is, in such embodiments, the fluid can be monitored off-line usinga standalone opticoanalytical device.

Other than when the opticoanalytical device is located in thesubterranean formation itself, the opticoanalytical device and the fluidthat it is monitoring are not generally in direct physical contact withone another. Generally, the opticoanalytical device can be in opticalcommunication with a fluid contained within a flow pathway, as describedpreviously. However, in some alternative embodiments, theopticoanalytical device can be in direct physical contact with the fluid(e.g., in a tank or within a flow pathway). FIG. 3 shows an illustrativeschematic demonstrating how an optical computing device can beimplemented along a flow pathway used for transporting a fluid. As shownin FIG. 3, source 300 produces incident electromagnetic radiation 301,which interacts with fluid 310 within line 303 having window 304 definedtherein. Window 304 is substantially transparent to incidentelectromagnetic radiation 301, allowing it to interact with fluid 310therein. Interacted electromagnetic radiation 302 is changed by itsinteraction with fluid 310, and it exits though window 304′, which issubstantially transparent to interacted electromagnetic radiation 302,thereby allowing fluid 310 to be in optical communication with opticalcomputing device 305. Some of interacted electromagnetic radiation 302is related to a component of interest in the fluid, and the remaininginteracted electromagnetic radiation 302 is due to interaction of theelectromagnetic radiation with background materials or other componentsin the fluid. Interacted electromagnetic radiation 302 then entersoptical computing device 305 having ICE 306 therein. ICE 306 thenseparates interacted electromagnetic radiation into components 307 and308, related to the component of interest and other components,respectively. Electromagnetic radiation component 307 then interactswith detector 309 to provide information on the component of interest influid 310. Further details of the operation of the optical computingdevice were set forth previously hereinabove. In some embodiments, theoutput of detector 309 can be a voltage signal, which can beproportional to the concentration of the component of interest.

In some embodiments, methods for analyzing the formation and transportof a treatment fluid can comprise: providing at least one sourcematerial; combining the at least one source material with a base fluidto form a treatment fluid; and monitoring a characteristic of thetreatment fluid using an opticoanalytical device. In some embodiments,the opticoanalytical device can be in optical communication with a flowpathway for transporting the treatment fluid (e.g., in-line monitoring).In other embodiments, monitoring a characteristic of the treatment fluidcan take place in an off-line manner.

Characteristics of the treatment fluid or source material that can bemonitored can include both physical and chemical properties.Characteristics of a treatment fluid or a source material that can bemonitored according to the present methods can include, without chemicalcomposition identity, chemical composition concentration, chemicalcomposition purity, viscosity, ionic strength, pH, total dissolvedsolids, total dissolved salt, density, and the like. In someembodiments, the characteristic of the treatment fluid can be determineddirectly from the output of a detector analyzing the electromagneticradiation reflected from, emitted by or transmitted through thetreatment fluid. For example, the identity and concentration of acomponent in a treatment fluid can be directly determined from adetector output (e.g., a voltage) based upon pre-established calibrationcurves. In other embodiments, the characteristic of the treatment fluidcan be calculated based upon a concentration of one or more componentsin the treatment fluid, as determined using the opticoanalytical device.For example, a processing element can determine the viscosity, pH, sagpotential, and/or any like physical property of the treatment fluidbased upon the content of one or more components of the treatment fluid.Further, in some embodiments, the processing element can determine acharacteristic of the treatment fluid based upon a linear combination ofproperty contributions from each component of the treatment fluid.

In some embodiments, the processing element to determine acharacteristic of the treatment fluid can be an artificial neuralnetwork, which can use training set information from treatment fluidshaving known properties and compositions in order to estimate thecharacteristics of treatment fluids having unknown content prior toanalysis. By determining a linear combination of property contributionsbased upon each component of the treatment fluid, a more accurateestimation of an unknown treatment fluid's properties can be determinedthan if the analysis was based upon a single component. That is, themore completely an artificial neural network is trained using treatmentfluids having known properties, the more likely it is to better estimatethe characteristics of an unknown treatment fluid.

By employing the present methods, at least in some embodiments, ameasure of quality control during the formation of a treatment fluid canbe established. Conventionally, treatment fluids are not rigorouslyanalyzed during their formation, or the analysis often can take placeafter the treatment fluid has already been introduced into asubterranean formation, at which point the analysis is only of use in aretrospective sense. The present methods overcome this limitation in theart and others by providing multiple opportunities to identify andadjust the characteristics of a treatment fluid before or during itsintroduction into a subterranean formation.

In some embodiments, a treatment fluid can be monitored immediatelyafter combining a base fluid and at least one source material to formthe treatment fluid. In some embodiments, monitoring can take place in avessel in which the treatment fluid is formed. In some embodiments,monitoring can take place as the treatment fluid exits the vessel inwhich the treatment fluid is formed. In some embodiments, monitoring cantake place as the treatment fluid is formed “on-the-fly.” In someembodiments, the treatment fluid can be monitored at one or more pointsas it is transported from the vessel to be introduced into asubterranean formation.

In some embodiments, the present methods can further comprisetransporting the treatment fluid to a pump after forming the treatmentfluid. In some embodiments, the methods can further comprise introducingthe treatment fluid into a subterranean formation, for example, by usingthe pump. In some embodiments, a characteristic of the treatment fluidcan be monitored using an opticoanalytical device that is in opticalcommunication with the fluid in a flow pathway to the subterraneanformation. In such embodiments, the opticoanalytical device can belocated at the pump or at a location near the pump, such that changes inthe characteristics of the treatment fluid between its formation andsubsequent introduction into a subterranean formation can be evaluated.The output from this opticoanalytical device can serve as the last lineof defense to prevent a treatment fluid having an incorrectcharacteristic from being introduced into a subterranean formation. Insome embodiments, transporting the treatment fluid to the pump can takeplace in a pipeline. In some embodiments, transporting the treatmentfluid to the pump can take place via a mobile transport means such as atruck or railway car. In some embodiments, transporting the treatmentfluid to the pump can take place by using a storage vessel on a boat orbarge for transporting the treatment fluid to an offshore site.

In some embodiments, the present methods can further comprisedetermining if the characteristic of the treatment fluid being monitoredmakes the treatment fluid suitable for being introduced into asubterranean formation. In various embodiments, determining if thetreatment fluid is suitable for being introduced into the subterraneanformation can comprise determining if one or more components thereinhave an out of range concentration, determining if an unwanted componentor other impurities are present, and/or determining if a physicalcharacteristic of the treatment fluid is out of range, for example.Other criteria for determining the suitability of a treatment fluid tobe introduced into a particular subterranean formation can beestablished by one having ordinary skill in the art. In someembodiments, determining if the characteristic makes the treatment fluidsuitable for being introduced into the subterranean formation can takeplace automatically. For example, a computer or like processing elementcan be configured to determine if the value of a characteristic beingmonitored or estimated represents an out of range condition. In someembodiments, monitoring and determining the suitability of a treatmentfluid for being introduced into a subterranean formation can take placevia remote monitoring and control.

Upon determining that the treatment fluid is unsuitable, the presentmethods can optionally further comprise adjusting a characteristic ofthe treatment fluid. In some embodiments, upon determining that thetreatment fluid is unsuitable for being introduced into the subterraneanformation, adjustment of a characteristic of the treatment fluid cantake place under operator control. For example, an operator can manuallydirect the addition of one or more components to the treatment fluid toadjust its composition and properties. The characteristic of thetreatment fluid can thereafter be re-evaluated and the suitability forintroduction into a subterranean formation determined. In someembodiments, the operator can manually add the one or more components tothe treatment fluid. In other embodiments, the operator can regulate anamount of one or more components being added to the treatment fluid fromone or more source streams. In some embodiments, adjustment of acharacteristic of the treatment fluid can take place automatically undercomputer control. For example, as described above, if a characteristicof the treatment fluid is determined to be out of range, a computer orlike processing element can direct that at least one component is addedto the treatment fluid to correct the out of range condition. In someembodiments, an additional amount of a component already in thetreatment fluid can be added to the treatment fluid until thecharacteristic being monitored is back in an acceptable range. In otherembodiments, at least one additional component can be added to thetreatment fluid in order to bring the characteristic being monitoredback into range. For example, in the case of an acidizing fluid, if theacid concentration is determined to be too high, a quantity of asuitable base can be added to neutralize some of the acid, or additionalbase fluid can be added to the treatment fluid in order to lessen theconcentration of the acid. In alternative embodiments, a component canbe removed from the treatment fluid in order to adjust itscharacteristics. As described previously, the impact of addingadditional components to a treatment fluid can impact othercharacteristics other than those being directly addressed, and when theadjustment takes place automatically under computer control, at least anestimation of the impact on these other characteristics can bedetermined. That is, when a characteristic of the treatment fluid isadjusted automatically, the computer or like processing element canevaluate if the chosen adjustment is expected to impact othercharacteristics of the treatment fluid in an undesired manner andcompensate for the adjustment of other characteristics, if needed.

In some embodiments, an operator can adjust or reset a set point or aset range for a characteristic of a fluid that is being automaticallycontrolled by computer. In some embodiments, an operator can direct theadjustment of a characteristic or change a set point for automaticcontrol by computer at the location of the treatment operation orthrough a communication system from a remote location.

In some embodiments, combining the base fluid and at least one componentof the treatment fluid can occur at the well head by “on-the-fly”addition of the at least one component. That is, the treatment fluid canbe formed at the well head without being transported from anotherlocation in such embodiments. Alternately, a pre-made treatment fluidcan be modified at the well head by on-the-fly addition of at least oneadditional component or adjusting the concentration of an existingcomponent in some embodiments. Advantages of on-the-fly addition caninclude, for example, reduced volumes, lower transportation costs,minimization of excess materials at a job site, and less opportunity fordegradation of the treatment fluid. Such on-the-fly addition does notallow the characteristics of the treatment fluid to be assayed accordingto conventional methodology before the treatment fluid is introducedinto the subterranean formation. This represents a particular difficultywith regard to control over a treatment operation, since it can often bedifficult to precisely determine how much of a component to add in orderto produce a treatment fluid having a desired characteristic. The samecan hold true even with treatment fluids that are pre-formulated beforebeing transported to a job site. However, these difficulties in the artcan be overcome through use of the methods of the present invention byusing opticoanalytical devices for monitoring the treatment fluid duringits formation and introduction into a subterranean formation.

In some embodiments, the present methods can further comprise monitoringa characteristic of at least one source material being used to form atreatment fluid by using an opticoanalytical device. In someembodiments, the opticoanalytical device can be in optical communicationwith a flow pathway for transporting the at least one source material.In some embodiments, the opticoanalytical device can be in a tank orother storage vessel housing the source material. In other embodiments,monitoring of the at least one source material can take place off-line.As discussed above, monitoring of the source material can serve as anadditional quality check during the formation of a treatment fluid.

In some embodiments, methods of the present invention can comprise:preparing a treatment fluid; transporting the treatment fluid to a jobsite; introducing the treatment fluid into a subterranean formation atthe job site; monitoring a characteristic of the treatment fluid at thejob site using an opticoanalytical device; determining if thecharacteristic of the treatment fluid being monitored using theopticoanalytical device makes the treatment fluid suitable for beingintroduced into the subterranean formation; and optionally, if thetreatment fluid is unsuitable, adjusting the characteristic of thetreatment fluid. In some embodiments, the opticoanalytical device can bein optical communication with a flow pathway for transporting thetreatment fluid. In other embodiments, monitoring using theopticoanalytical device can take place off-line.

In some embodiments, methods of the present invention can comprise:providing a treatment fluid that comprises a base fluid and at least oneadditional component; introducing the treatment fluid into asubterranean formation; and monitoring a characteristic of the treatmentfluid using at least a first opticoanalytical device. In someembodiments, the opticoanalytical device can be in optical communicationwith a flow pathway for transporting the treatment fluid before thetreatment fluid is introduced into the subterranean formation. In otherembodiments, monitoring using the opticoanalytical device can take placeoff-line before the treatment fluid is introduced into the subterraneanformation.

In some embodiments, methods of the present invention can comprise:forming a treatment fluid on-the-fly by adding at least one component toa base fluid stream; introducing the treatment fluid into a subterraneanformation; and monitoring a characteristic of the treatment fluid whileit is being introduced into the subterranean formation using anopticoanalytical device. In some embodiments, the methods can furthercomprise: determining if the characteristic of the treatment fluid beingmonitored using the opticoanalytical device makes the treatment fluidsuitable for being introduced into the subterranean formation, andoptionally, if the treatment fluid is unsuitable, adjusting thecharacteristic of the treatment fluid.

Monitoring Fluids in and Produced from a Subterranean Formation

In some embodiments, the present methods can further compriseintroducing the treatment fluid into a subterranean formation. In someembodiments, the introduction into the subterranean formation can takeplace after determining that the treatment fluid is suitable for beingintroduced into the subterranean formation. In some embodiments, thetreatment fluid can be modified while it is being introduced into thesubterranean formation by adding at least one additional componentthereto or adjusting the concentration of an existing component. In someembodiments, the treatment fluid can be modified while it is in asubterranean formation. According to the present embodiments, monitoringof a treatment fluid in the subterranean formation or in a flow backfluid produced therefrom occurs in-process. Further, according to someof the present embodiments, a formation fluid can be monitored using anopticoanalytical device in the formation or in optical communicationwith a fluid being produced from the formation.

Additional information regarding the effectiveness of a treatmentoperation can be obtained by continued monitoring of the treatment fluidor a formation fluid while it is downhole or after the treatment fluidor formation fluid is produced from the subterranean formation.Monitoring of formation fluids (e.g. oil) while within the subterraneanformation or after their production from the subterranean formation canalso provide information on the effectiveness of a treatment operationand/or provide guidance on how a treatment operation can be modified inorder to increase production. In some embodiments, the present methodscan further comprise monitoring a characteristic of the treatment fluidand/or a formation fluid using an opticoanalytical device positioned inthe formation. In other embodiments, the present methods can furthercomprise monitoring a characteristic of a fluid produced from asubterranean formation. The produced fluid can be a produced formationfluid in some embodiments or a treatment fluid produced as a flow backfluid in other embodiments. In some embodiments, the flow back fluidand/or the produced formation fluid can be monitored using anopticoanalytical device that is in optical communication with a flowpathway for transporting the flow back fluid. In some embodiments, theflow back fluid can comprise an at least partially spent treatment fluidfrom the performance of a subterranean treatment operation.

In some embodiments, the present methods can further comprise performinga treatment operation in the subterranean formation, and monitoring acharacteristic of the treatment fluid and/or the formation fluid afterthe treatment fluid is introduced into the subterranean formation usingan opticoanalytical device. In some embodiments, the treatment fluidand/or formation fluid can be monitored using an opticoanalytical devicethat is located in the subterranean formation. In some embodiments, thetreatment fluid and/or formation fluid can be monitored using anopticoanalytical device that is in optical communication with a flowpathway for transporting a flow back fluid or formation fluid producedfrom the subterranean formation. In some embodiments, monitoring in thesubterranean formation or of the flow back fluid and/or producedformation fluid can be conducted in-process during the performance of atreatment operation.

In some embodiments, the present methods can further comprise adjustinga characteristic of the treatment fluid being introduced into thesubterranean formation in response to the characteristic of thetreatment fluid or formation fluid being monitored using theopticoanalytical device in the formation or in optical communicationwith the flow back fluid pathway. For example, if the opticoanalyticaldevice in the formation or monitoring the flow back fluid indicates thata component of the treatment fluid is spent, or that the treatment fluidno longer has a desired characteristic for adequately performing atreatment operation, the treatment fluid being introduced into thesubterranean formation can be adjusted so as to modify at least onecharacteristic thereof, as described previously. Similarly, monitoringof the formation fluid can be used in models that evaluate theeffectiveness of a treatment operation, for example. In someembodiments, adjustment of the characteristic of the treatment fluid inresponse to a characteristic measured in the formation or in the flowback fluid can take place automatically under computer control.

In some embodiments, methods described herein can comprise: providing atreatment fluid comprising a base fluid and at least one additionalcomponent; introducing the treatment fluid into a subterraneanformation; allowing the treatment fluid to perform a treatment operationin the subterranean formation; and monitoring a characteristic of thetreatment fluid or a formation fluid using at least a firstopticoanalytical device. In some embodiments, the characteristic of thetreatment fluid or the formation fluid can be monitored within theformation using the first opticoanalytical device. In some embodiments,the characteristic of the treatment fluid can be monitored in a flowback fluid produced from the formation, where the flow back fluidcontains treatment fluid from the treatment operation. In someembodiments, the formation fluid can be monitored during production. Insome embodiments, the characteristic of the treatment fluid and/or theformation fluid can both be monitored.

When monitoring a characteristic of the treatment fluid afterintroduction into a subterranean formation, monitoring thecharacteristic can comprise, in some embodiments, monitoring at leastthe identity and concentration of at least one component in thetreatment fluid, the flow back fluid, or both. According to suchembodiments, if one knows the concentration of the component prior tointroduction into the subterranean formation, the change inconcentration of the component while in the subterranean formation orafter production from the subterranean formation (optionally incombination with information on the formation fluid) can provideinformation about the effectiveness of the treatment operation beingconducted. For example, if the concentration of the component fails tochange after being introduced into the subterranean formation, it canlikely be inferred that the treatment operation had minimal to no effecton the subterranean formation. Likewise, if the concentration of thecomponent decreases after being introduced into the subterraneanformation, it is probable that the formation has been modified in someway by the treatment fluid. By monitoring the concentration of acomponent in a treatment fluid and/or formation fluid before and afterintroduction of the treatment fluid into a subterranean formation, acorrelation between the effectiveness of a treatment operation can beestablished, in some embodiments. For example, the change inconcentration of a component can be correlated to the effectiveness of atreatment operation being performed in the subterranean formation.Furthermore, if the treatment fluid becomes completely spent upon beingintroduced into the subterranean formation (that is, the concentrationof at least one component therein drops below an effective level or evenbecomes zero), this can alert an operator or an automated systemoverseeing the treatment operation that the treatment fluid potentiallyneeds to be altered or that the treatment operation potentially needs tobe repeated, for example.

In order to determine a change in concentration of at least onecomponent in a treatment fluid, the present methods can further comprisemonitoring a characteristic of the treatment fluid before the treatmentfluid is introduced into the subterranean formation. According to suchembodiments, the (pre-introduction characteristic can serve as abaseline value for establishing whether a change in the characteristichas occurred upon being introduced into the subterranean formation. Insome embodiments, the characteristic of the treatment fluid before itsintroduction into the subterranean formation can be used as a basis foradjusting the characteristic of the treatment fluid being introducedinto the subterranean formation.

In some embodiments, the present methods can further comprisedetermining if the characteristic of the treatment fluid beingintroduced into the subterranean formation needs to be adjusted inresponse to the characteristic of the treatment fluid or the formationfluid being monitored in the subterranean formation or in the flow backfluid using the opticoanalytical device. In some embodiments, thepresent methods can further include adjusting the characteristic of thetreatment fluid being introduced into the subterranean formation inresponse to the characteristic of the treatment fluid or the formationfluid monitored in the subterranean formation or in the flow back fluid.In some embodiments, adjusting the characteristic of the treatment fluidcan take place automatically under computer control. In someembodiments, an artificial neural network can be used in the adjustmentof the treatment fluid.

In some embodiments, tracers and/or probes can be deployed in thetreatment fluids used in the present methods. As used herein, the term“tracer” refers to a substance that is used in a treatment fluid toassist in the monitoring of the treatment fluid in a subterraneanformation or in a flow back fluid being produced from a subterraneanformation. Illustrative tracers can include, for example, fluorescentdyes, radionuclides, and like substances that can be detected inexceedingly small quantities. A tracer typically does not conveyinformation regarding the environment to which it has been exposed,unlike a probe. As used herein, the term “probe” refers to a substancethat is used in a treatment fluid to interrogate and deliver informationregarding the environment to which it has been exposed. Upon monitoringthe probe, physical and chemical information regarding a subterraneanformation can be obtained.

In some embodiments, the present methods can further comprise monitoringa tracer or a probe in a treatment fluid using an opticoanalyticaldevice. In some embodiments, the tracer or probe can be monitored in theflow back fluid produced from the subterranean formation. In otherembodiments, the tracer or probe can be monitored within thesubterranean formation. In the case of probes being monitored within asubterranean formation, the present methods can be particularlyadvantageous, since a probe that is produced in the flow back fluid cansometimes be altered such that it no longer conveys an accuraterepresentation of the subterranean environment to which it has beenexposed. In some embodiments, tracers or probes in the treatment fluidcan be monitored using the opticoanalytical devices in order todetermine a flow pathway for the treatment fluid in the subterraneanformation. In some embodiments, monitoring of tracers or probes can beused to determine the influence of diverting agents on the flow pathway.Conventional methods for monitoring downhole fluid flow pathways caninclude, for example, distributed temperature sensing, as described incommonly owned United States Patent Application Publication2011/0048708, which is incorporated herein by reference in its entirety.

In some embodiments, the treatment fluid being monitored by the presentmethods can be an aqueous treatment fluid. That is, the treatment fluidscan comprise an aqueous base fluid. Suitable aqueous base fluids caninclude those set forth above. In some embodiments, a suitable aqueousbase fluid can be produced water from a subterranean formation. Theproduced water can be formation water, in some embodiments, or therecovered aqueous base fluid from another aqueous treatment fluid inother embodiments. The aqueous base fluid can be monitored using anopticoanalytical device according to some of the present embodiments, asdescribed elsewhere herein.

Monitoring of Produced Water and Reuse Thereof

Water treatment, conservation and management are becoming increasinglyimportant in the oilfield industry. Oftentimes, significant waterproduction can accompany hydrocarbon production in a well, whether fromformation water or water used in a stimulation operation for the well.Increasingly strict environmental regulations have made disposal of thiswater a significant issue. Due to the volumes of water involved(millions of gallons per well), storage of this water while awaitingconventional analyses can be highly problematic. Water analysesconducted according to the embodiments described herein can address someof these limitations in the art and provide related advantages as well.

In some embodiments, the methods of the present invention can be appliedtoward monitoring a water obtained from a water source. In particular,in some embodiments, the water can comprise the base fluid being used toform a treatment fluid. In some embodiments, the water can be monitoredto determine its suitability for disposal or for determining itscharacteristics in order to ascertain a remediation protocol to make itsuitable for disposal. In some embodiments, methods of the presentinvention can comprise determining the suitability of a water for use asthe base fluid of a treatment fluid and, if the water is not suitablefor a particular treatment fluid, adjusting at least one characteristicof the water to make it suitable.

In some embodiments, the water being monitored by the methods of thepresent invention can be a produced water from a subterranean formation.The produced water can be formation water in some embodiments and/orcomprise water from a base fluid that was part of a treatment fluid thatperformed a treatment operation in the subterranean formation (i.e., anaqueous flow back fluid) in other embodiments. As used herein, the term“produced water” refers to water obtained from a subterranean formation,regardless of its source. By determining the characteristics of theproduced water, the suitability of the water for disposal or recyclingas a base fluid in a subsequent treatment operation can be determined.

In some embodiments, methods described herein can comprise: providingwater from a water source; monitoring a characteristic of the waterusing an opticoanalytical device; and introducing the water into asubterranean formation. In some embodiments, the opticoanalytical devicecan be in optical communication with a flow pathway for transporting thewater.

In some embodiments, the water can be fresh water, acidified water, saltwater, seawater, brine, aqueous salt solutions, saturated saltsolutions, municipal water, municipal waste water, or produced water.The water source can be a surface water source such as, for example, astream, a pond, an ocean, a detention pond, or a detention tank. Inother embodiments, the water source can be a subterranean formation thatprovides the produced water. In some embodiments, a produced water canbe formation water. In other embodiments, a produced water can be anaqueous flow back fluid obtained following a treatment operation. Insome embodiments, the produced water can be a combination of formationwater and an aqueous flow back fluid.

In some embodiments, the present methods can further comprisedetermining if the water is suitable for being introduced into thesubterranean formation, and optionally, if the water is unsuitable,adjusting the characteristic of the water. As noted previously,determining the suitability of a fluid for introduction into asubterranean formation can be vital to the “health” of the subterraneanformation, as the introduction of unwanted components can actuallydamage the subterranean formation or lead to an ineffective treatmentoperation. For example, the introduction of the wrong treatment fluid toa subterranean formation can lead to unwanted precipitation therein.Similarly, introduction of a treatment fluid containing bacteria canlead to biofouling or related damage that can impact production from asubterranean formation.

In some embodiments, the water can be introduced directly into thesubterranean formation. For example, the water can be introduced intothe subterranean formation as part of a water flooding operation. Insome embodiments, the water can comprise a tracer or probe when beingintroduced into the subterranean formation. In some embodiments, thepresent methods can further comprise monitoring the tracer or probe inthe subterranean formation using an opticoanalytical device or in a flowback fluid produced from the subterranean formation.

In some embodiments, the water introduced into the subterraneanformation can be used for environmental monitoring. That is, the waterintroduced into a subterranean formation can be monitored at well sitesremote from the injection point to ascertain the movement of a fluidthrough and out of a subterranean formation. In some embodiments, anopticoanalytical device of the present invention can be used formonitoring the water at the remote well sites. In some embodiments,tracers or probes can be used in the water when environmental monitoringapplications are conducted.

In other embodiments, the water can be introduced into the subterraneanformation in a treatment fluid. That is, in some embodiments, thetreatment fluid can comprise the water. In some embodiments, a propertyof the water can be adjusted by adding at least one additional componentto the water. In some embodiments, the combination of the water and theat least one other component can be considered to constitute thetreatment fluid. In other embodiments, a property of the water can beadjusted by adding at least one other component to the water prior toforming the treatment fluid, and still another additional component canbe added thereafter to form the treatment fluid. That is, a treatmentfluid formed in such a manner comprises at least two additionalcomponents. A reason one might form a treatment fluid in this manner isif a characteristic of the unmodified water would be detrimental to acomponent being used to form the treatment fluid. In this case, a firstcomponent could be added to adjust the characteristic of the water so asto no longer be detrimental to the second component being addedsubsequently. In alternative embodiments, a property of the water can beadjusted by removing at least one component from the water prior toforming a treatment fluid or by performing at least one water treatmenton the water.

In some embodiments, methods of the present invention can furthercomprise combining at least one additional component with the water soas to alter at least one property thereof. In some embodiments, themethods can further comprise monitoring a characteristic of the waterusing an opticoanalytical device after adding the at least oneadditional component. In some embodiments, monitoring the characteristicof the water after adding the at least one additional component can takeplace using an opticoanalytical device that is in optical communicationwith a flow pathway for transporting the water. In such embodiments, theopticoanalytical device can be used to ascertain if the at least oneadditional component has altered the characteristic of the water indesired fashion. For example, after adding the at least one additionalcomponent, the opticoanalytical device can be used to determine if acomponent added to the water (which can be a component already in thewater) lies within a desired concentration range. In alternativeembodiments, monitoring of the water using the opticoanalytical devicecan take place offline. In some embodiments, combining the at least oneadditional component with the water can take place automatically undercomputer control in response to a characteristic of the water monitoredusing an opticoanalytical device. In some embodiments, remote monitoringand adjustment can be conducted.

In some embodiments, methods of the present invention can comprise:producing water from a first subterranean formation, thereby forming aproduced water; monitoring a characteristic of the produced water usingan opticoanalytical device; forming a treatment fluid comprising theproduced water and at least one additional component; and introducingthe treatment fluid into the first subterranean formation or a secondsubterranean formation. In some embodiments, the opticoanalytical devicecan be in optical communication with a flow pathway for transporting theproduced water. In other embodiments, monitoring the characteristic ofthe water using the opticoanalytical device can take place off-line.

In some embodiments, the methods can further comprise monitoring acharacteristic of the treatment fluid using another opticoanalyticaldevice. In some embodiments, the opticoanalytical device used formonitoring the treatment fluid can be in optical communication with aflow pathway for transporting the treatment fluid. In other embodiments,monitoring of the treatment fluid using the opticoanalytical device cantake place off-line. In some embodiments, the treatment fluid can bemonitored using the opticoanalytical device before it has beenintroduced into the subterranean formation. In other embodiments, thetreatment fluid can be monitored after it has been introduced into thesubterranean formation, either in the formation itself or in a flow backfluid produced from the subterranean formation. In some embodiments, theformation fluid can also be monitored.

In some embodiments, methods of the present invention can comprise:providing water from a water source; monitoring a characteristic of thewater using an opticoanalytical device; and treating the water so as toalter at least one property thereof. In some embodiments, treating thewater can be conducted in response to the characteristic of the watermonitored using the opticoanalytical device. In some embodiments, theopticoanalytical device can be in optical communication with a flowpathway for transporting the water.

In some embodiments, treating the water can comprise adding at least onecomponent to the water. In some embodiments, treating the water cancomprise increasing the concentration of an existing component in thewater. In other embodiments, treating the water can comprise removing atleast one component from the water. For example, the water can besubjected to a water purification technique. Illustrative waterpurification techniques are well known in the art and can include, forexample, filtration, treatment with activated carbon, ion-exchange,reverse osmosis and the like. Generally, these water purificationtechniques remove at least one component from the water or modify atleast one component in the water in order to modify the water'sproperties. In some embodiments, the water can be monitored with anopticoanalytical device after the water treatment takes place in orderto determine if the water has the characteristics desired. In someembodiments, treating the water can comprise a bactericidal treatmentsuch as, for example, exposure to ultraviolet light, electrocoagulation,or ozonolysis.

In some embodiments, the water can be selectively treated to remove,inactivate, or destroy components that can interfere with the formationof a treatment fluid or the effectiveness of a treatment fluid in asubterranean formation. For example, a water treatment process can bedesigned to render the water suitable for use in a treatment fluidwithout complete purification being achieved. Suitable water treatmentprocesses for oilfield treatment fluids are described in commonly ownedU.S. patent application Ser. Nos. 12/722,410; 13/007,363; and13/007,369, each of which is incorporated herein by reference in itsentirety.

In some embodiments, the present methods can further comprise disposingof the water after treating the water. In such embodiments, the watertreatment can be chosen so as to make the water suitable for disposal.In some embodiments, the water can be monitored using anopticoanalytical device after being treated so as to verify that thewater has been modified in a desired way, thereby making it suitable fordisposal. In alternative embodiments, the water can be disposed ofwithout additional treatment taking place if it is determined, using anopticoanalytical device, that the water is already suitable fordisposal.

In some embodiments, water being produced from a subterranean formationcan be recycled for use as the base fluid of a treatment fluid beingintroduced into the same subterranean formation or a differentsubterranean formation. Various types of treatment fluids that can beproduced and monitored according to the methods described herein havebeen set forth previously. Depending on the intended treatmentoperation, the characteristic(s) of the water being monitored willlikely vary from application to application. For example, whenperforming a fracturing operation, the certain ionic species, ifpresent, can impact the outcome of a fracturing operation. Likewise, inan acidizing operation, particularly of a silica-containing subterraneanformation, the presence of calcium ions in the base fluid can causeunwanted precipitation during the acidizing operation. In some cases,the water can contain materials that, if present, can lead toineffective crosslinking of crosslinking agents and therefore impact thetreatment fluid's rheological profile.

In some embodiments, treatment fluids comprising water, particularlywater produced from a subterranean formation, can be used as fracturingfluids. In such embodiments, the treatment fluid can be introduced intoa subterranean formation at a pressure sufficient to create or enhanceat least one fracture therein. In some embodiments, monitoring acharacteristic of a water to be used in a treatment operation cancomprise monitoring the water for an ionic material. In this regard, thepresent methods can be particularly advantageous, since certain ionicmaterials, if present, can detrimentally impact a fracturing operation.These ionic materials can include, for example, iron-containing ions(e.g., Fe²⁺, Fe³⁺ and iron containing complex ions), iodine-containingions (e.g., I⁻ and I₃ ⁻), boron-containing ions (e.g., BO₃ ⁻), sulfurcontaining ions (e.g., SO₄ ²⁻, SO₃ ²⁻ and S²⁻), barium ions, strontiumions, magnesium ions, or any combination thereof. Other components ofthe water can also be detrimental to fracturing operations and will berecognized by one having ordinary skill in the art. For example, otherionic materials that can be of interest to monitor in a water caninclude, for example, carbonate ions, sodium ions, potassium ions,aluminum ions, calcium ions, manganese ions, lithium ions, cesium ions,chromium ions, fluoride ions, chloride ions, bromide ions, iodide ions,arsenic ions, lead ions, mercury ions, nickel ions, copper ions, zincions, titanium ions and the like. In addition, the presence of certaindissolved minerals in the water can also be of interest. Neutralmolecules such as, for example, molecular iodine and boric acid can alsobe problematic as well. Still further, dissolved organic compounds inthe water can also be monitored by using opticoanalytical devicesaccording to the present methods.

Without being bound by any theory or mechanism in the followingdiscussion, it is believed that certain ionic materials can bedetrimental to fracturing operations for a number of different reasons.For example, sodium and potassium ions can affect hydration of polymers.Other ions such as, for example, borate, iron, sodium and aluminum ionscan compete for crosslinking sites. In addition, some characteristics ofa water can affect the ability to control the pH of a fluid producedtherefrom. All of these factors can influence the overall rheologicalproperties and ultimate performance of a fracturing fluid.

In some embodiments, detection of the ionic materials can take placedirectly using the opticoanalytical device. In some embodiments, theopticoanalytical device can be specifically configured to detect theionic materials of interest. In other embodiments, dyes or othermolecular tags can be used that react with the ionic materials in orderto produce a detectable species. That is, the opticoanalytical devicecan be specifically configured to detect the reaction product of the dyeor tag with the ionic species. Dyes and tags can be used, for example,when the ionic species is not readily detectable alone or if thesensitivity is not as great as desired. Other types of components in thewater can be detected using dyes and tags as well.

It should be noted that the monitoring of water obtained from a watersource is not limited to ionic materials. For example, in someembodiments, neutral substances (e.g., boric acid, molecular iodine, andorganic compounds) can be monitored. In other embodiments, biologicssuch as bacteria and the like can be monitored using the presentmethods.

In some embodiments, upon identification of a substance in the waterthat is known to be detrimental to fracturing operations or another typeof treatment operation, a characteristic of the water can be adjusted byadding at least one additional component thereto. In some embodiments,the addition of the at least one additional component to the water cancreate a treatment fluid having a custom formulation that is nottypically used when a water source having a relatively consistentcomposition is used for forming a treatment fluid. Specifically, a waterfrom a surface water source can many times have a composition that isrelatively consistent from batch to batch, unless a contamination eventhas occurred, allowing treatment fluids having known, relativelyconstant compositions to be formulated. In contrast, a produced watercan have a widely varying composition from batch to batch, depending onthe type of subterranean formation from which it was obtained and anytreatment operation that was previously performed in the subterraneanformation. In order to address the variable characteristics of producedwater, an array of additional components can be added thereto, some ofwhich may not be commonly used in treatment fluids. In this regard,methods of the present invention can be particularly advantageous, asthey can be capable of addressing the widely varying compositionsencountered in produced waters by making predictive estimations ofproperties and conducting automatic adjustment and monitoring of thoseproperties under computer control during the addition of at least onecomponent to the produced water.

Applications to Fracturing Fluids and Fracturing Operations

In some embodiments, methods of the present invention can be used tomonitor the formation of fracturing fluids and the performance offracturing fluids during fracturing operations conducted in asubterranean formation. In addition to the issues with fracturing fluidsnoted above, other fracturing components in the fracturing fluid can bemonitored using the present methods to determine the suitability of afracturing fluid for performing a fracturing operation and to evaluatethe effectiveness of a fracturing operation. Particularly, the presentmethods can be used to monitor a characteristic of a fracturing fluidduring its formation and subsequent introduction into a subterraneanformation at a pressure sufficient to create or enhance at least onefracture therein.

As non-limiting examples of how the present methods can be advantageousfor monitoring a fracturing fluid, the present methods can be used tomonitor a fracturing fluid's viscosity or the type of proppantparticulates therein. A fracturing fluid having an insufficientviscosity may not have the capacity for supporting a proppant in thefracturing fluid, thereby leading to the failure of a fracturingoperation. Likewise, the wrong type, size or concentration of proppantparticulates can lead to the failure of a fracturing operation. Similarcharacteristics can be monitored during a fracturing operation in orderto evaluate its effectiveness.

According to the present embodiments, the fracturing fluid can compriseany number of fracturing fluid components. In at least some embodiments,the fracturing fluid can contain at least a base fluid and proppantparticulates, in addition to other fracturing fluid components. Otherfracturing fluid components that can be present in the fracturing fluidinclude, for example, a surfactant, a gelling agent, a crosslinkingagent, a crosslinked gelling agent, a diverting agent, a salt, a scaleinhibitor, a corrosion inhibitor, a chelating agent, a polymer, ananti-sludging agent, a foaming agent, a buffer, a clay control agent, aconsolidating agent, a breaker, a fluid loss control additive, arelative permeability modifier, a tracer, a probe, nanoparticles, aweighting agent, a rheology control agent, a viscosity modifier (e.g.,fibers and the like), and any combination thereof. Any of thesefracturing fluid components can influence the characteristics of thefracturing fluid and can be monitored according to the methods describedherein using opticoanalytical devices.

In some embodiments, methods for forming a fracturing fluid cancomprise: providing at least one fracturing fluid component; combiningthe at least one fracturing fluid component with a base fluid to form afracturing fluid; and monitoring a characteristic of the fracturingfluid using an opticoanalytical device. In some embodiments, theopticoanalytical device can be in optical communication with a flowpathway for transporting the fracturing fluid.

In some embodiments, monitoring a characteristic of the fracturing fluidcan comprise monitoring at least the identify and concentration of theat least one fracturing fluid component in the fracturing fluid by usingthe opticoanalytical device. For example, in some embodiments, theidentity and concentration of proppant particulates or a surfactant canbe monitored in the fracturing fluid. In some embodiments, monitoring acharacteristic of the fracturing fluid can comprise monitoring thefracturing fluid for impurities using the opticoanalytical device. Insome embodiments, the impurities can be known impurities, where theopticoanalytical device has been configured to detect those impurities.In other embodiments, the impurities can be unknown impurities, wherethe presence of the impurities can be inferred by the characteristics ofthe fracturing fluid determined by the opticoanalytical device.

In some embodiments, the present methods can further comprisetransporting the fracturing fluid to a pump, and introducing thefracturing fluid into a subterranean formation at a pressure sufficientto create or enhance at least one fracture therein. In some embodiments,a characteristic of the fracturing fluid can be monitored while beingtransported to the pump by using an opticoanalytical device located atthe pump.

In some embodiments, the present methods can further comprisedetermining if the characteristic of the fracturing fluid beingmonitored makes the fracturing fluid suitable for being introduced intothe subterranean formation, and optionally, if the fracturing fluid isunsuitable, adjusting the characteristic of the fracturing fluid. Insome embodiments, determining if the fracturing fluid is suitable andadjusting the characteristic of the fracturing fluid can take placeautomatically under computer control. In some embodiments, adjusting thecharacteristic of the fracturing fluid can take place manually. In someembodiments, adjusting, the characteristic of the fracturing fluid cancomprise adjusting, the concentration of at least one fracturing fluidcomponent in the fracturing fluid or adding at least one additionalfracturing fluid component to the fracturing fluid.

In some embodiments, monitoring the characteristic of the fracturingfluid and adjusting the characteristic of the fracturing fluid can takeplace by remote monitoring. Automated control and remote operation canbe particularly advantageous for fracturing operations. Information fromthe opticoanalytical devices can be integrated with fracturing equipmentinformation in real-time or near real-time to monitor and controlfracturing operations. In addition, the fracturing information,including information from opticoanalytical devices, can be sent bysatellite, wide area network systems or other communication systems to aremote location to further enhance job execution. Monitoring and controlof the fracturing operation can then take place from this remotelocation. In some embodiments, remote operation can take placeautomatically under computer control.

In some embodiments, the present methods can further compriseintroducing the fracturing fluid into a subterranean formation at apressure sufficient to create or enhance at least one fracture therein.In some embodiments, the methods can further comprise monitoring acharacteristic of the fracturing fluid or a formation fluid using anopticoanalytical device within the subterranean formation. In someembodiments, the present methods can further comprise producing a flowback fluid from the subterranean formation and monitoring acharacteristic of the flow back fluid or a produced formation fluidusing an opticoanalytical device. In some embodiments, theopticoanalytical device monitoring the flow back fluid or producedformation fluid can be in optical connection with a flow pathway fortransporting the flow back fluid.

In some embodiments, methods described herein can comprise: providing afracturing fluid comprising at least one fracturing fluid component;introducing the fracturing fluid into a subterranean formation at apressure sufficient to create or enhance at least one fracture therein;and monitoring a characteristic of the fracturing fluid using anopticoanalytical device. In some embodiments, the opticoanalyticaldevice can be in optical communication with a flow pathway fortransporting the fracturing fluid before introducing the fracturingfluid into the subterranean formation.

In some embodiments, the methods can further comprise performing afracturing operation in the subterranean formation and monitoring acharacteristic of the fracturing fluid or a formation fluid after thefracturing fluid is introduced into the subterranean formation usinganother opticoanalytical device. In such embodiments, theopticoanalytical device can be located in the subterranean formation orin optical communication with a flow pathway for transporting a flowback fluid produced from the subterranean formation. In someembodiments, the characteristic of the fracturing fluid being introducedinto the subterranean formation can be adjusted in response to thecharacteristic of the fracturing fluid or the formation fluid beingmonitored using the opticoanalytical device in the subterraneanformation or monitoring the flow back fluid or produced formation fluid.

In some embodiments, methods for monitoring a fracturing fluid cancomprise: forming a fracturing fluid on-the-fly by adding at least onefracturing fluid component to a base fluid stream; introducing thefracturing fluid into a subterranean formation at a pressure sufficientto create or enhance at least one fracture therein; and monitoring acharacteristic of the fracturing fluid while it is being introduced intothe subterranean formation using an opticoanalytical device. In someembodiments, the methods can further comprise determining if thecharacteristic of the fracturing fluid being monitored using theopticoanalytical device makes the fracturing fluid suitable for beingintroduced into the subterranean formation, and, optionally, if thefracturing fluid is unsuitable, adjusting the characteristic of thefracturing fluid.

In some embodiments, methods described herein can comprise: providing afracturing fluid comprising a base fluid and at least one fracturingfluid component; introducing the fracturing fluid into a subterraneanformation at a pressure sufficient to create or enhance at least onefracture therein, thereby performing a fracturing operation in thesubterranean formation; and monitoring a characteristic of thefracturing fluid or a formation fluid using an opticoanalytical device.In some embodiments, the characteristic of the fracturing fluid or theformation fluid can be monitored in-process within the subterraneanformation, in a flow back fluid or formation fluid produced from thesubterranean formation, or both, while the fracturing operation is beingconducted.

In some embodiments, the methods can further comprise determining if thecharacteristic of the fracturing fluid being introduced into thesubterranean formation needs to be adjusted in response to aconcentration of at least one fracturing component being monitored withan opticoanalytical device in the subterranean formation, or in opticalcommunication with a flow pathway of a flow back fluid being producedfrom the subterranean formation. In some embodiments, the methods canfurther comprise adjusting the characteristic of the fracturing fluidbeing introduced into the subterranean formation. In some embodiments,determining if the characteristic of the fracturing fluid needs to beadjusted and adjusting the characteristic of the fracturing fluid cantake place automatically under computer control.

In some embodiments, methods for performing a fracturing operation canfurther comprise monitoring a characteristic of the fracturing fluidusing an opticoanalytical device that is in optical communication with aflow pathway for transporting the fracturing fluid, where monitoringtakes place before the fracturing fluid is introduced into thesubterranean formation. In some embodiments, the methods can comprisedetermining a change in concentration of at least one fracturing fluidcomponent, based upon monitoring of the component before and after thefracturing fluid is introduced into the subterranean formation. In someembodiments, the change in concentration of the at least one fracturingfluid component can be correlated to an effectiveness of the fracturingoperation being conducted in the subterranean formation. In someembodiments, the concentration of a component in a formation fluid canlikewise be correlated to an effectiveness of the fracturing operationas well.

Analyses of produced fluids resulting from a fracturing operation (i.e.,flow back fluids and formation fluids) can be used in models to estimatereservoir and fracture properties. The methods described herein can beused to supplement and beneficially increase the speed of theseanalyses, in particular, the composition of flowback water and formationwater can be modeled to obtain information on permeability,conductivity, fracture dimensional features, and related information(See Gdanski et al, “A New Model for Matching Fracturing Fluid FlowbackComposition,” SPE 106040 presented at the 2007 SPE Hydraulic FracturingTechnology Conference held in College Station, Tex., U.S.A., Jan. 29-31,2007 and Gdanski et at, “Using Lines-of-Solutions to Understand FractureConductivity and Fracture Cleanup,” SPE 142096 presented at the SPEProduction and Operations Symposium held in Oklahoma City, Okla.,U.S.A., Mar. 27-29, 2011). Methods for estimating properties of asubterranean formation and determining fracture characteristics in asubterranean formation from flowback fluid data are also described incommonly owned U.S. Pat. No. 7,472,748, which is incorporated herein byreference in its entirety.

In some embodiments, a tracer or probe in the fracturing fluid can bemonitored using an opticoanalytical device. Monitoring the tracer orprobe can also be beneficial for determining the effectiveness of afracturing operation. For example, by monitoring a tracer or probe inthe fracturing fluid using an opticoanalytical device, a flow pathwaywithin the subterranean formation can be determined, in someembodiments.

In some embodiments, the present methods can be used to monitor a flowpathway of a fracturing fluid to which has been added a diverting agent.For example, one or more opticoanalytical devices in a subterraneanformation can be used to determine where a fracturing fluid or othertreatment fluid is flowing before the diverting agent is added to thetreatment fluid. After the diverting agent is added, theopticoanalytical devices can be used to determine if the flow pathwayhas changed within the subterranean formation.

In some embodiments, methods described herein can comprise: providing afracturing fluid comprising a base fluid and at least one fracturingfluid component; introducing the fracturing fluid into a subterraneanformation at a pressure sufficient to create or enhance at least onefracture therein; and monitoring a characteristic of the fracturingfluid using an opticoanalytical device before the fracturing fluid isintroduced into the subterranean formation. In some embodiments, theopticoanalytical device can be in optical communication with a flowpathway for transporting the fracturing fluid. In some embodiments, themethods can further comprise monitoring a characteristic of thefracturing fluid or a formation fluid after the fracturing fluid isintroduced into the subterranean formation, where the fracturing fluidcan be monitored in-process within the subterranean formation or in aflow back fluid produced from the subterranean formation.

In some embodiments, the present methods can further comprise monitoringat least the identity and concentration of at least one fracturing fluidcomponent using an opticoanalytical device, before the fracturing fluidcomponent is used to form a treatment fluid. In some embodiments,monitoring the at least one fracturing fluid component can be conductedwith an opticoanalytical device that is in optical communication with aflow pathway for transporting the fracturing fluid component. In otherembodiments, the opticoanalytical device can be located in a storagevessel for the fracturing fluid component.

Applications to Acidizing Fluids and Acidizing Operations

In some embodiments, methods of the present invention can be used tomonitor the formation of acidizing fluids and the performance ofacidizing operations in a subterranean formation. In variousembodiments, the acidizing fluids can contain at least one acid. Mosttypically, the at least one acid can be selected from hydrochloric acid,hydrofluoric acid, formic acid, acetic acid, glycolic acid, lactic acid,and the like. Hydrochloric acid is typically used for acidizinglimestone and carbonate-containing subterranean formations. Hydrofluoricacid is typically used for acidizing silicate-containing formations,including sandstone. It should be recognized by one having ordinaryskill in the art that other acids or mixtures of acids can be used aswell. The choice of an acid blend suitable for a particular subterraneanformation will most often be a matter of routine design for one havingordinary skill in the art. In addition, suitable compounds that formacids downhole (i.e., acid precursors) can also be used. For example,esters, orthoesters and degradable polymers such as polylactic acid canbe used to generate an acid in the subterranean formation. As one ofordinary skill in the art will also appreciate, the introduction of anacidizing fluid not having the proper characteristics or compositionduring an acidizing operation can have significant consequences on thesuccess thereof, as damage to the subterranean formation can occur ifthe wrong acid is used. For example, precipitation of formation solidscan occur in certain instances.

In addition to at least one acid, acidizing fluids suitable for use inthe present embodiments can also contain other components in addition tothe at least one acid. Two of the more notable components are chelatingagents and/or corrosion inhibitors, for example. Chelating agents canslow or prevent the precipitation of formation solids, even when theproper acid is used during the treatment operation. Corrosion inhibitorscan slow or prevent the degradation of metal tools used during theperformance of an acidizing operation. If either of these components areout of range in an acidizing fluid being introduced into a subterraneanformation, serious consequences in the performance of an acidizingoperation can result. Other components that can optionally be present inthe acidizing fluid include for example, a surfactant, a gelling agent,a salt, a scale inhibitor, a polymer, an anti-sludging agent, adiverting agent, a foaming agent, a buffer, a clay control agent, aconsolidating agent, a breaker, a fluid loss control additive, arelative permeability modifier, a tracer, a probe, nanoparticles, aweighting agent, a rheology control agent, a viscosity modifier, and anycombination thereof. Any of these additional components can also bemonitored using an opticoanalytical device according to the methodsdescribed herein.

In some embodiments, methods for forming an acidizing fluid cancomprise: providing at least one acid; combining the at least one acidwith a base fluid to form an acidizing fluid; and monitoring acharacteristic of the acidizing fluid using an opticoanalytical device.In some embodiments, the opticoanalytical device can be in opticalcommunication with a flow pathway for transporting the acidizing fluid.

In some embodiments, monitoring a characteristic of the acidizing fluidcan comprise monitoring at least the identity and concentration of theat least one acid in the acidizing fluid by using the opticoanalyticaldevice. In some embodiments, monitoring a characteristic of theacidizing fluid can comprise monitoring at least the identity andconcentration of at least one additional component in the acidizingfluid using the opticoanalytical device. Additional components caninclude those set forth above. In some embodiments, monitoring acharacteristic of the acidizing fluid can comprise monitoring theacidizing fluid for impurities using the opticoanalytical device. Insome embodiments, the impurities can be known impurities, where theopticoanalytical device has been configured to detect those impurities.In other embodiments, the impurities can be unknown impurities, wherethe presence of the impurities can be inferred by the characteristics ofthe acidizing fluid determined by the opticoanalytical device.

In some embodiments, the present methods can further comprisetransporting the acidizing fluid to a pump, and introducing theacidizing fluid into a subterranean formation. In some embodiments, acharacteristic of the acidizing fluid can be monitored using anopticoanalytical device white being transported to the pump. In someembodiments, the opticoanalytical device can be located at the pump.

In some embodiments, the present methods can further comprisedetermining if the characteristic of the acidizing fluid being monitoredmakes the acidizing fluid suitable for being introduced into thesubterranean formation, and optionally, if the acidizing fluid isunsuitable, adjusting the characteristic of the acidizing fluid. In someembodiments, adjusting the characteristic of the acidizing fluid cantake place automatically under computer control. In some embodiments,adjusting the characteristic of the acidizing fluid can take placemanually. In some embodiments, adjusting the characteristic of theacidizing fluid can comprise adjusting the concentration of the at leastone acid therein. In some embodiments, adjusting the characteristic ofthe acidizing fluid can take place through remote monitoring andcontrol.

In some embodiments, the present methods can further compriseintroducing the acidizing fluid into a subterranean formation. In someembodiments, the methods can further comprise monitoring acharacteristic of the acidizing fluid or a formation fluid using anopticoanalytical device within the subterranean formation. In someembodiments, the present methods can further comprise producing a flowback fluid from the subterranean formation and monitoring acharacteristic of the flow back fluid or a produced formation fluidusing an opticoanalytical device that is in optical communication with aflow pathway for transporting the flow back fluid. In some embodiments,monitoring a characteristic of the acidizing fluid in the subterraneanformation or in the flow back fluid produced from the subterraneanformation can occur in-process while an acidizing operation is beingperformed.

In some embodiments, the present methods can further comprise adjustinga characteristic of the acidizing fluid being introduced into thesubterranean formation in response to a characteristic of the acidizingfluid being monitored using an opticoanalytical device located at a pumpfor introducing the acidizing fluid into the subterranean formation.

In some embodiments, methods described herein can comprise: providing anacidizing fluid comprising at least one acid; introducing the acidizingfluid into a subterranean formation; and monitoring a characteristic ofthe acidizing fluid using an opticoanalytical device. In someembodiments, the opticoanalytical device can be in optical communicationwith a flow pathway for transporting the acidizing fluid.

In some embodiments, the methods can further comprise performing anacidizing operation in the subterranean formation, and monitoring acharacteristic of the acidizing fluid or a formation fluid after theacidizing fluid is introduced into the subterranean formation usinganother opticoanalytical device. In such embodiments, theopticoanalytical device can be located in the subterranean formation orin optical communication with a flow pathway for transporting a flowback fluid produced from the subterranean formation. In someembodiments, the characteristic of the acidizing fluid being introducedinto the subterranean formation can be adjusted in response to thecharacteristic of the acidizing fluid or formation fluid being monitoredusing the opticoanalytical device in the subterranean formation ormonitoring the flow back fluid.

In some embodiments, methods described herein can comprise: forming anacidizing fluid on-the-fly by adding at least one acid to a base fluidstream; introducing the acidizing fluid into a subterranean formation;and monitoring a characteristic of the acidizing fluid using anopticoanalytical device while the acidizing fluid is being introducedinto the subterranean formation. In some embodiments, the methods canfurther comprise determining if the characteristic of the acidizingfluid being monitored using the opticoanalytical device makes theacidizing fluid suitable for being introduced into the subterraneanformation, and, optionally, if the acidizing fluid is unsuitable,adjusting the characteristic of the acidizing fluid.

In some embodiments, methods for performing an acidizing operation cancomprise: providing an acidizing fluid comprising a base fluid and atleast one acid; introducing the acidizing fluid into a subterraneanformation; allowing the acidizing fluid to perform an acidizingoperation in the subterranean formation; and monitoring a characteristicof the acidizing fluid or a formation fluid using an opticoanalyticaldevice. In some embodiments, the characteristic of the acidizing fluidor the formation fluid can be monitored in-process within thesubterranean formation, in a flow back fluid produced from thesubterranean formation, or both.

In some embodiments, monitoring a characteristic of the acidizing fluidcan comprise monitoring at least the identity and concentration of theat least one acid in the acidizing fluid, the flow back fluid, or both.In some embodiments, the methods can further comprise determining if thecharacteristic of the acidizing fluid being introduced into thesubterranean formation needs to be adjusted in response to theconcentration of the at least one acid being monitored using theopticoanalytical device in the subterranean formation or in opticalcommunication with a flow pathway for transporting a flow back fluidproduced therefrom. In some embodiments, the methods can furthercomprise adjusting the characteristic of the acidizing fluid beingintroduced into the subterranean formation. In some embodiments,determining if the characteristic of the acidizing fluid needs to beadjusted and adjusting the characteristic of the acidizing fluid cantake place automatically under computer control.

In some embodiments, the methods can further comprise monitoring acharacteristic of the acidizing fluid using an opticoanalytical devicebefore the acidizing fluid is introduced into the subterraneanformation. In some embodiments, the opticoanalytical device can be inoptical communication with a flow pathway for transporting the acidizingfluid. In some embodiments, a change in concentration of at least oneacid or other component in the acidizing fluid can be determined bymonitoring the acidizing fluid before and after it is introduced intothe subterranean formation. In some embodiments, the change inconcentration of the at least one acid or other component in theacidizing fluid can be correlated to an effectiveness of an acidizingoperation being conducted in the subterranean formation.

In some embodiments, a tracer or probe in the acidizing fluid or theflow back fluid can be monitored using an opticoanalytical deviceaccording to the present methods.

In some embodiments, methods described herein can comprise: providing anacidizing fluid comprising a base fluid and at least one acid;introducing the acidizing fluid into a subterranean formation; andmonitoring a characteristic of the acidizing fluid using anopticoanalytical device before the acidizing fluid is introduced intothe subterranean formation. In some embodiments, the opticoanalyticaldevice can be in optical communication with a flow pathway fortransporting the acidizing fluid.

In some embodiments, the methods can further comprise determining if thecharacteristic of the acidizing fluid being introduced into thesubterranean formation needs to be adjusted in response to thecharacteristic of the acidizing fluid being monitored using theopticoanalytical device. In some embodiments, the methods can furthercomprise adjusting the characteristic of the acidizing fluid. In someembodiments, determining if the characteristic of the acidizing fluidneeds to be adjusted and adjusting the characteristic of the acidizingfluid can take place automatically under computer control.

In some embodiments, the methods can further comprise monitoring acharacteristic of the acidizing fluid or a formation fluid in-processusing an opticoanalytical device, where the characteristic is measuredin the subterranean formation, in a flow back fluid produced from thesubterranean formation, or both.

Monitoring of Bacteria

In some embodiments, the methods described hereinabove can be extendedto the monitoring of bacteria in a fluid, particularly a treatment fluidin a subterranean formation or being introduced into a subterraneanformation. The monitoring of bacteria in or near real-time is presentlybelieved to be unfeasible using current spectroscopic techniques,particularly at low bacterial levels. The present methods can overcomethis limitation in the art.

In particular regard to subterranean operations, water used in varioussubterranean operations can be obtained from a number of “dirty” watersources, having varying levels of bacterial contamination therein.Although bacterial contamination may not be particularly problematic intreatment fluid when it is on the surface, once the treatment fluid isintroduced into a warm subterranean environment, even low levels ofbacteria can multiply quickly, potentially leading to damage of thesubterranean formation. In some cases, biofouling of the surface of thesubterranean formation can occur. Specifically, anaerobic H₂S-producingbacteria, can be particularly detrimental to subterranean operations.Rapidly multiplying bacteria, and their metabolic byproducts can quicklyclog and corrode production tubulars, plug formation fractures andproduce H₂S which presents a health hazard and can lead to completionfailure and loss of production. Accordingly, it is highly desirable toreduce bacteria levels in a treatment fluid before it is introduced intoa subterranean formation.

A number of techniques are known for killing bacteria to reducebacterial loads in a sample (e.g., exposure to ultraviolet light,ozonolysis, electrocoagulation, biocidal treatments and the like).However, it is believed that no current techniques are available forreal-time or near real-time monitoring of bacterial load and formonitoring the effectiveness of a bactericidal treatment process todetermine if bacterial load in a sample has been reduced to a sufficientdegree. Without being bound by theory or mechanism, it is believed thatbactericidal treatments such as, for example, ultraviolet lightexposure, rapidly alter the deoxyribonucleic acid (DNA) and/orribonucleic acid (RNA) of the bacteria, sometimes in conjunction withrupturing of their cell walls, to result in their eventual death.

In some embodiments, opticoanalytical devices described herein can beused to monitor bacteria according to the present embodiments bymonitoring the DNA or RNA of the bacteria, and the changes thereto, as aresult of a bactericidal treatment. The opticoanalytical devices, insome embodiments, can be configured for detecting the DNA or RNA of livebacteria, and the increase or decrease in the amount of DNA or RNA canbe used to effectively monitor the amount of live bacteria in thesample. In some embodiments, the opticoanalytical devices can beconfigured to detect the DNA or RNA of specific types of bacteria. Insome embodiments, fluorescent emission from the DNA or RNA can be usedas an extremely sensitive detection technique for the DNA or RNA. Thus,the present methods can be suitable for fluids having low bacterialloads (e.g., as low as about 1000 bacteria/mL). As increasing numbers ofbacteria have their DNA or RNA changed by the bactericidal treatment,the amount detected by the opticoanalytical devices will correspondinglydecrease. The decrease in the amount of DNA or RNA can be directlycorrelated to the number of viable bacteria in the sample.Correspondingly, if it observed that the amount of DNA or RNA in asample is increasing, the increase can be indicative of bacterialgrowth, which can suggest the necessity for performing a bactericidaltreatment. In alternative embodiments, dead or dying bacteria that havealtered DNA or RNA can also be monitored by the present methods,provided that the opticoanalytical device is configured for the alteredDNA or RNA of these species.

In some embodiments, methods described herein can comprise: monitoringbacteria in water using an opticoanalytic device that is in opticalcommunication with the water. In some embodiments, the water can beflowing through a flow pathway while monitoring the bacteria takesplace. In some embodiments, the bacteria can be live bacteria. In otherembodiments, the bacteria can be dead or dying bacteria. In someembodiments, monitoring can take place on a static water sample. Inother embodiments, monitoring can take place while the water is flowingthrough a flow pathway.

In some embodiments, methods for monitoring bacteria can comprise:exposing water to a bactericidal treatment; and after exposing the waterto the bactericidal treatment, monitoring live bacteria in the waterusing an opticoanalytical device that is in optical communication withthe water.

In some embodiments, the monitoring live bacteria in the water cancomprise monitoring DNA or RNA from the live bacteria. As notedpreviously, the DNA or RNA of the live bacteria can be distinguishedfrom the DNA or RNA of dead, dying or non-viable bacteria due to astructural change affected by a bactericidal treatment in someembodiments, the present methods can comprise detecting and analyzing anemission of fluorescent radiation from the live bacteria (e.g., from theDNA or RNA of the live bacteria). In some or other embodiments,non-viable bacteria (i.e., dead or dying bacteria) can be monitoredaccording to the present methods by utilizing the fingerprint of theiraltered DNA or RNA.

In some embodiments, monitoring the live bacteria in the water cancomprise monitoring the types of bacteria, the quantity of bacteria, orboth in the water. In some embodiments, it may be of interest todetermine if specific types of bacteria are in the water, and theopticoanalytical devices can be specifically configured to detectdifferent types of bacteria based upon differences in their DNA or RNA“fingerprint.” In other embodiments, it may be more of interest tosimply determine the number of bacteria in the water (i.e., thebacterial load), and the present methods can be used in this regard aswell by configuring the opticoanalytical devices for less specific DNAor RNA detection.

Illustrative bactericidal treatments can include, for example, exposureof the bacteria to ultraviolet light, electrocoagulation, ozonolysis, orintroduction of a chemical biocide to the water. In particular, exposureto ultraviolet light can be an especially facile mechanism for killingbacteria, since a very rapid alteration of their DNA or RNA can occurupon exposure to ultraviolet light. Various illustrative bactericidaltreatments are described in more detail in commonly owned U.S. Pat. No.7,332,094, which is incorporated herein by reference in its entirety,and in commonly owned U.S. patent application Ser. Nos. 12/683,337 (U.S.Patent Application Publication 2011/0163046) and 12/683,343 (U.S. PatentApplication Publication 2011/0166046), each of which is incorporatedherein by reference in its entirety.

In some embodiments, the methods can further comprise determining a killratio for the bacteria that has been affected by the bactericidaltreatment. The kill ratio can be determined, in some embodiments, bymeasuring the live bacterial load before and after a bactericidaltreatment is performed. In some embodiments, the kill ratio can be atleast about 75%. In other embodiments, the kill ratio can be at leastabout 80%, or at least about 85%, or at least about 90%, or at leastabout 95%, or at least about 96%, or at least about 97%, or at leastabout 98%, or at least about 99%, in some embodiments, if a desired killratio is not attained, the methods can further comprise repeating thebactericidal treatment or performing a different bactericidal treatment.

In other embodiments, methods for monitoring bacteria can comprise:monitoring live bacteria in a water source using an opticoanalyticaldevice that is in optical communication with the water source; and aftermonitoring the live bacteria in the water source, exposing the water toa bactericidal treatment. In some embodiments, the methods can furthercomprise monitoring the live bacteria in the water using anopticoanalytical device that is in optical communication with the waterafter the bactericidal treatment takes place.

In some embodiments, the present methods can further comprisedetermining if the water is suitable for being introduced into asubterranean formation. In some embodiments, determining if the water issuitable can be based upon the total number of live bacteria in thewater. For example, if an excessive number of live bacteria aredetected, the water can be unsuitable. In some embodiments, determiningif the water is suitable can be based upon the presence of certain typesof bacteria in the water, particularly above a given bacterial load. Forexample, the presence of H₂S-producing bacteria in the water can makethe water unsuitable for being introduced into a subterranean formation.In addition, the mere presence of certain types of bacteria, in thewater can make the water unsuitable for being introduced into asubterranean formation.

In some embodiments, the present methods can further comprise forming atreatment fluid comprising the water and at least one additionalcomponent; and introducing the treatment fluid into a subterraneanformation. In alternative embodiments, a water that is suitable forbeing introduced into subterranean formation can be directly introducedinto a subterranean formation without forming a treatment fluid (e.g.,for a water flooding operation). In some embodiments, the presentmethods can further comprise monitoring the treatment fluid in thesubterranean formation using another opticoanalytical device located inthe subterranean formation. In some embodiments, the opticoanalyticaldevice can be used to monitor live bacteria in the treatment fluid anddetermine if a bactericidal treatment needs to be applied to thetreatment fluid in the subterranean formation. In other embodiments, theopticoanalytical device in the subterranean formation can be used tomonitor another characteristic of the treatment fluid according to theembodiments previously described herein.

In some embodiments, methods for monitoring bacteria, can comprise:providing a treatment fluid comprising a base fluid and at least oneadditional component; monitoring live bacteria in the treatment fluidusing an opticoanalytical device that is in optical communication with aflow pathway for transporting the treatment fluid; and after monitoringthe live bacteria in the treatment fluid, introducing the treatmentfluid into a subterranean formation after monitoring the live bacteriatherein. In some embodiments, the treatment fluid can be flowing in theflow pathway while monitoring the bacteria takes place. In otherembodiments, the treatment fluid can be static while monitoring thebacteria.

In some embodiments, the present methods can further comprisedetermining a bactericidal treatment for the treatment fluid based uponthe types of bacteria and the quantity of bacteria therein, as monitoredusing the opticoanalytical device, and performing the bactericidaltreatment on the treatment fluid. In some embodiments, determining abactericidal treatment for the treatment fluid can take placeautomatically under computer control. For example, based upon the typesand number of bacteria in the treatment fluid, an artificial neuralnetwork can determine appropriate bactericidal treatment times,concentrations, and the like to predict how bacterial loads can bereduced in a treatment fluid. In some embodiments, the methods canfurther comprise monitoring live bacteria in the treatment fluid usingan opticoanalytical device after performing the bactericidal treatmenton the treatment fluid. Monitoring the bacteria in the treatment fluidafter performing the bactericidal treatment can be used to assess theeffectiveness of the bactericidal treatment prior to introducing thetreatment fluid into the subterranean formation.

In some embodiments, the methods can further comprise monitoring livebacteria in the treatment fluid while the treatment fluid is located ina subterranean formation by using another opticoanalytical devicelocated in the subterranean formation, in some embodiments, theopticoanalytical device in the subterranean formation can be used todetermine if bacterial loads in the subterranean formation have exceededdesired levels. In some embodiments, based upon the bacteria monitoredin the subterranean formation, the present methods can further compriseadding a bactericidal agent to the treatment fluid in the subterraneanformation.

In some embodiments, methods for monitoring bacteria can comprise:providing a treatment fluid comprising a base fluid and at least oneadditional component; introducing the treatment fluid into asubterranean formation; and monitoring live bacteria in the treatmentfluid within the subterranean formation using an opticoanalytical devicelocated therein. In some embodiments, the methods can further compriseadding a bactericidal agent to the treatment fluid within thesubterranean formation. In some embodiments, the methods can furthercomprise monitoring live bacteria in the treatment fluid within thesubterranean formation using the opticoanalytical device therein afteradding the bactericidal agent.

Monitoring of Fluid Streams

More generally, methods described hereinabove using opticoanalyticaldevices for monitoring treatment fluids and various components thereincan be extended to monitoring the characteristics of fluid streams,particularly fluid streams that are being modified by an operator orunder computer control, particularly remote monitoring by an operator orartificial neural network, in order to produce a desired effect in thefluid stream. As previously noted, fluid streams can be operativelylinked to a great number of industrial processes, and the ability tomonitor such fluids can be a significant process advantage, particularlywhen the monitoring can be conducted in-process. For example, fluids canchange over time as a result of their use in an industrial process (orsimply degrade), and the ability to rapidly monitor and respond to thesechanges can greatly improve process efficiency. Specifically, in someembodiments, opticoanalytical devices can be used to determine when afluid needs to be replaced by monitoring its characteristics. In otherembodiments, opticoanalytical devices can be used to determine when afluid needs to be treated in order to adjust its characteristics, and infurther embodiments, the opticoanalytical devices can be used to monitoran action taken to adjust the characteristics of the fluid.

In some embodiments, methods for monitoring a fluid can comprise:providing a fluid in a fluid stream; and monitoring a characteristic ofthe fluid using an opticoanalytical device that is in opticalcommunication with the fluid in the fluid stream. In some embodiments,the methods can further comprise determining if the characteristic ofthe fluid needs to be adjusted based upon an output of theopticoanalytical device, and, optionally, if the characteristic of thefluid needs to be adjusted, performing an action on the fluid in thefluid stream to adjust the characteristic of the fluid.

In general, an action that can be taken on a fluid in order to adjustits characteristics can include any chemical, physical, or biologicalprocess that is undertaken in order to adjust its properties. Anycombination or chemical, physical and/or biological processes can beused to adjust the characteristics of the fluid. In some embodiments, anaction that can be performed on a fluid can comprise adding at least onecomponent to the fluid or increasing the concentration of the componentin the fluid. For example, in non-limiting embodiments, an acid can beadded or increased in concentration to lower the pH of a fluid, or aviscosifying agent can be added or increased in concentration to modifythe rheological properties of a fluid. In some embodiments, an actionthat can be performed on a fluid can comprise removing at least onecomponent from the fluid or reducing the concentration of the componentin the fluid. For example, in non-limiting embodiments, a fluid can besubjected to ion exchange to remove ionic species therefrom, or afiltration step can be conducted to remove particulate matter from thefluid. In still other embodiments, an action that can be performed on afluid can comprise exposing the fluid to a bactericidal treatment oranother type of purification treatment known in the art. As describedabove, bacterial growth in fluids can present significant issues.Bactericidal treatments can include any of those set forth previouslyhereinabove. It is to be recognized that the foregoing examples ofactions that can be performed on a fluid in order to adjust itscharacteristics should be considered illustrative in nature only, andone having ordinary skill in the art will be able to select anappropriate action to perform on a fluid in order to affect itsproperties in a desired way.

In some embodiments, after an action has been performed on the fluid inorder to modify its characteristics, the fluid can again be monitoredwith an opticoanalytical device to determine if the action taken has hadthe desired effect. In some embodiments, the present methods cancomprise monitoring a characteristic of the fluid using anopticoanalytical device that is in optical communication with the fluidin the fluid stream, after an action has been taken on the fluid tomodify its characteristics. Accordingly, if the characteristic of thefluid has been modified in a desired way and returned to an in-rangevalue, use of the fluid can continue. Likewise, if the characteristic ofthe fluid has not been returned to an in-range value, the action canagain be performed on the fluid or a different action can be selected tobe performed on the fluid.

In some embodiments, various operations in the monitoring of thecharacteristics of a fluid can take place automatically under computercontrol. In some embodiments, computer control can be used to determineif the characteristic of the fluid needs to be adjusted. In someembodiments, an action can be performed on the fluid to adjust thecharacteristic. In some embodiments, the action performed on the fluidcan take place under computer control. For example, computer control canbe used to assess an out of range characteristic in a fluid anddetermine an appropriate corrective course of action. Thereafter,computer control can be used to automatically carry out the action usedfor adjusting the characteristic of the fluid.

In general, any type of fluid in a fluid stream can be monitoredaccording to the present embodiments. Fluids suitable for use in thepresent embodiments can include, for example, flowable solids, liquidsand/or gases. In some embodiments, the fluid can be water or an aqueousfluid containing water. In other embodiments, the fluid can comprise anorganic compound, specifically a hydrocarbon, an oil, a refinedcomponent of oil, or a petrochemical. Furthermore, the fluids streamscan be operatively coupled to any type of process or used in any type ofindustrial setting. For example, in some embodiments, the fluid streamcan comprise a water stream that is operatively coupled to a coolingtower or like heat transfer mechanism. In other embodiments, the fluidstream can be located in a refinery or chemical plant. When used in suchlocations, the fluid stream can comprise a coolant stream in someembodiments, a reactant feed stream in some embodiments, or a productfeed stream in other embodiments. Thus, the present methods can be usedto confirm that the correct materials are being supplied to and producedfrom an industrial process, as well as monitor background fluid use thatis used in carrying out the process.

In some embodiments, methods for monitoring a fluid can comprise:providing a fluid in a fluid stream; monitoring a characteristic of thefluid using an opticoanalytical device that is in optical communicationwith the fluid in the fluid stream; determining if the characteristic ofthe fluid needs to be adjusted based upon an output from theopticoanalytical device; performing an action on the fluid in the fluidstream so as to adjust the characteristic; and after performing theaction on the fluid in the fluid stream, monitoring the characteristicof the fluid using another opticoanalytical device that is in opticalcommunication with the fluid in the fluid stream.

In some embodiments, methods for monitoring water can comprise:providing water in a fluid stream; performing an action on the water inthe fluid stream so as to adjust a characteristic of the water; afterperforming the action on the water in the fluid stream, monitoring thecharacteristic of the water using an opticoanalytical device that is inoptical communication with the water in the fluid stream; anddetermining if the characteristic of the water lies within a desiredrange. In some embodiments, performing an action on the water cancomprise at least one action such as, for example, adding at least onecomponent to the water or increasing the concentration of the component,removing at least one component from the water or reducing theconcentration of the component, exposing the water to a bactericidaltreatment or another purification treatment, and any combinationthereof. In some embodiments, the methods can further comprise repeatingthe action on the water or performing another action on the water, ifthe characteristic of the water does not lie in a desired range. In someembodiments, determining if the characteristic of the water lies withina desired range and repeating the action on the water and/or performinganother action on the water can take place automatically under computercontrol.

Although a number of industrial processes use and produce fluids, it isbelieved that the present methods can be particularly beneficial incooling tower and refinery applications. In both of these applications,it can be important to maintain fluid integrity during fluid input andoutput. In regard to refinery applications, the present methods can beapplied to monitoring the fluid input and output of the material beingrefined being refined. For example, in some embodiments,opticoanalytical devices can be used to monitor very viscous fluids suchas 30 gravity oil in order to monitor process integrity.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered,combined, or modified and all such variations are considered within thescope and spirit of the present invention. While compositions andmethods are described in terms of “comprising,” “containing,” or“including” various components or steps, the compositions and methodscan also “consist essentially of” or “consist of” the various componentsand steps. All numbers and ranges disclosed above may vary by someamount. Whenever a numerical range with a lower limit and an upper limitis disclosed, any number and any included range falling within the rangeis specifically disclosed, in particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b,” or, equivalently, “from approximately a-b” disclosed herein is tobe understood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an,” as used in theclaims, are defined herein to mean one or more than one of the elementthat it introduces. If there is any conflict in the usages of a word orterm in this specification and one or more patent or other documentsthat may be incorporated herein by reference, the definitions that areconsistent with this specification should be adopted.

What is claimed is the following:

1. A method comprising: providing at least one acid; combining the atleast one acid with a base fluid to form an acidizing fluid; andmonitoring a characteristic of the acidizing fluid using a firstopticoanalytical device that is in optical communication with a flowpathway for transporting the acidizing fluid.
 2. The method of claim 1,further comprising: before combining, monitoring at least the identityand concentration of the at least one acid using a secondopticoanalytical device that is in optical communication with a flowpathway for transporting the at least one acid.
 3. The method of claim1, wherein monitoring a characteristic of the acidizing fluid comprisesmonitoring at least the identity and concentration of the at least oneacid in the acidizing fluid using the first opticoanalytical device. 4.The method of claim 1, wherein monitoring a characteristic of theacidizing fluid comprises monitoring at least the identity andconcentration of at least one additional component in the acidizingfluid using the first opticoanalytical device.
 5. The method of claim 4,wherein the at least one additional component comprises a substanceselected from the group consisting of a surfactant, a gelling agent, asalt, a scale inhibitor, a corrosion inhibitor, an anti-sludging agent,a diverting agent, a chelating agent, a foaming agent, a buffer, a claycontrol agent, a consolidating agent, a breaker, a fluid loss controladditive, a relative permeability modifier, a tracer, a probe, and anycombination thereof.
 6. The method of claim 1, wherein monitoring acharacteristic of the acidizing fluid comprises monitoring the acidizingfluid for impurities using the first opticoanalytical device.
 7. Themethod of claim 1, further comprising: transporting the acidizing fluidto a pump; and introducing the acidizing fluid into a subterraneanformation.
 8. The method of claim 7, further comprising: monitoring acharacteristic of the acidizing fluid using a second opticoanalyticaldevice that is in optical communication with a flow pathway fortransporting the acidizing fluid; wherein the second opticoanalyticaldevice is located at the pump.
 9. The method of claim 8, furthercomprising: determining if the characteristic of the acidizing fluidbeing monitored using either the first or the second opticoanalyticaldevice makes the acidizing fluid suitable for being introduced into thesubterranean formation; and optionally, adjusting the characteristic ofthe acidizing fluid.
 10. The method of claim 9, wherein determining ifthe characteristic of the acidizing fluid makes the acidizing fluidsuitable and adjusting the characteristic of the acidizing fluid bothoccur automatically under computer control.
 11. The method of claim 1,further comprising: introducing the acidizing fluid into a subterraneanformation.
 12. The method of claim 11, further comprising: while theacidizing fluid is in the subterranean formation, monitoring acharacteristic of the acidizing fluid or a formation fluid using asecond opticoanalytical device that is located in the subterraneanformation.
 13. The method of claim 11, further comprising: producing aflow back fluid from the subterranean formation; and monitoring acharacteristic of the flow back fluid or a produced formation fluidusing a second opticoanalytical device that is in optical communicationwith a flow pathway for transporting the flow back fluid.
 14. The methodof claim 11, further comprising: adjusting the characteristic of theacidizing fluid being introduced into the subterranean formation inresponse to a characteristic of the acidizing fluid being monitoredusing a second opticoanalytical device that is in optical communicationwith a flow pathway for transporting the acidizing fluid; wherein thesecond opticoanalytical device is located at a pump used for introducingthe acidizing fluid into the subterranean formation.
 15. The method ofclaim 14, wherein adjusting the characteristic of the acidizing fluidbeing introduced into the subterranean formation occurs automaticallyunder computer control.
 16. A method comprising: providing an acidizingfluid comprising at least one acid; introducing the acidizing fluid intoa subterranean formation; and monitoring a characteristic of theacidizing fluid using a first opticoanalytical device that is in opticalcommunication with a flow pathway for transporting the acidizing fluid.17. The method of claim 16, further comprising: determining if thecharacteristic of the acidizing fluid being monitored using the firstopticoanalytical device makes the acidizing fluid suitable for beingintroduced into the subterranean formation; and optionally, adjustingthe characteristic of the acidizing fluid.
 18. The method of claim 17,wherein determining if the characteristic of the acidizing fluid makesthe acidizing fluid suitable and adjusting the characteristic of theacidizing fluid both occur automatically under computer control.
 19. Themethod of claim 16, wherein monitoring a characteristic of the acidizingfluid comprises monitoring at least the identity and concentration ofthe at least one acid in the acidizing fluid using the firstopticoanalytical device.
 20. The method of claim 16, further comprising:performing an acidizing operation in the subterranean formation; andmonitoring a characteristic of the acidizing fluid or a formation fluidafter the acidizing fluid is introduced into the subterranean formationusing a second opticoanalytical device that is located in thesubterranean formation or is in optical communication with a flowpathway for transporting a flow back fluid produced therefrom.
 21. Themethod of claim 20, further comprising: adjusting the characteristic ofthe acidizing fluid being introduced into the subterranean formation inresponse to the characteristic of the acidizing fluid or the formationfluid being monitored using the second opticoanalytical device.
 22. Themethod of claim 16, wherein monitoring the characteristic of theacidizing fluid takes place at least before the acidizing fluid isintroduced into the subterranean formation.
 23. A method comprising:forming an acidizing fluid on-the-fly by adding at least one acid to abase fluid stream; introducing the acidizing fluid into a subterraneanformation; and monitoring a characteristic of the acidizing fluid usingan opticoanalytical device while the acidizing fluid is being introducedinto the subterranean formation.
 24. The method of claim 23, furthercomprising: determining if the characteristic of the acidizing fluidbeing monitored using the opticoanalytical device makes the acidizingfluid suitable for being introduced into the subterranean formation; andoptionally, adjusting the characteristic of the acidizing fluid.